Up-regulation of the chondrogenic Sox9 gene by fibroblast growth factors is mediated by the mitogen-activated protein kinase pathway
Up-regulation of the chondrogenic Sox9 gene by fibroblast growth factors is mediated by the mitogen-activated protein kinase pathway
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DOI：
10.1073/pnas.97.3.1113
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发表时间：
2000-02-01
影响因子：
11.1
通讯作者：
de Crombrugghe, B
中科院分区：
文献类型：
--
作者：
Murakami, S;Kan, M;de Crombrugghe, B
最近的实验证实 Sox9 是软骨细胞分化所必需的。在这里，我们发现成纤维细胞生长因子（FGF）显着增强小鼠原代软骨细胞以及表达低水平 Sox9 的 C3H10T1/2 细胞中的 Sox9 表达，FGF 还强烈增加 II 型胶原基因中依赖 Sox9 的软骨细胞特异性增强子的活性。使用编码 FGF 受体的构建体进行的瞬时转染实验强烈表明，所有 FGF 受体 FGFR1-R4 都可以转导导致 Sox9 表达增加的信号。原代软骨细胞中特定的丝裂原激活蛋白激酶激酶 (MAPKK)/丝裂原激活蛋白激酶/ERK 激酶 (MEK) 抑制剂 U0126 抑制 FGF2 诱导的 Sox9 水平增加。此外，还共表达双特异性磷酸酶 CL100/MKP-1。能够使丝裂原激活蛋白激酶 (MAPK) 去磷酸化和失活，抑制 FGF2 诱导的 Sox9 依赖性增强子活性增加。此外，MEK1 的组成型活性突变体的共表达增加了原代软骨细胞和 C3H10T1/2 细胞中 Sox9 依赖性增强子的活性，模拟了 FCF 的作用。这些结果表明，软骨细胞以及未分化间充质细胞中的 FGF 刺激主要软骨形成因子 Sox9 基因的表达，并强烈表明这种调节是由 MAPK 途径介导的。由于 Sox9 对于软骨细胞分化至关重要，因此我们认为 FGF 和 MAPK 通路在软骨形成中发挥重要作用。
Recent experiments have established that Sox9 is required for chondrocyte differentiation. Here, we show that fibroblast growth factors (FGFs) markedly enhance Sox9 expression in mouse primary chondrocytes as well as in C3H10T1/2 cells that express low levels of Sox9, FGFs also strongly increase the activity of a Sox9-dependent chondrocyte-specific enhancer in the gene for collagen type II. Transient transfection experiments using constructs encoding FGF receptors strongly suggested that all FGF receptors, FGFR1-R4, can transduce signals that lead to the increase in Sox9 expression. The increase in Sox9 levels induced by FGF2 was inhibited by a specific mitogen-activated protein kinase kinase (MAPKK)/mitogen-activated protein kinase/ERK kinase (MEK) inhibitor U0126 in primary chondrocytes. In addition, coexpression of a dual-specificity phosphatase, CL100/MKP-1. that is able to dephosphorylate and inactivate mitogen-activated protein kinases (MAPKs) inhibited the FGF2-induced increase in activity of the Sox9-dependent enhancer. Furthermore, coexpression of a constitutively active mutant of MEK1 increased the activity of the Sox9-dependent enhancer in primary chondrocytes and C3H10T1/2 cells, mimicking the effects of FCFs. These results indicate that expression of the gene for the master chondrogenic factor Sox9 is stimulated by FGFs in chondrocytes as well as in undifferentiated mesenchymal cells and strongly suggest that this regulation is mediated by the MAPK pathway. Because Sox9 is essential for chondrocyte differentiation, we propose that FGFs and the MAPK pathway play an important role in chondrogenesis.