Fibroblast growth factor inhibits chondrocytic growth through induction of p21 and subsequent inactivation of cyclin E-Cdk2
Fibroblast growth factor inhibits chondrocytic growth through induction of p21 and subsequent inactivation of cyclin E-Cdk2
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DOI：
10.1074/jbc.m101859200
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发表时间：
2001-08-03
影响因子：
4.8
通讯作者：
Lee, K
中科院分区：
文献类型：
--
作者：
Aikawa, T;Segre, GV;Lee, K
成纤维细胞生长因子（FGF）及其受体（FGFR）被认为是软骨细胞生长的负调节因子，如软骨发育不全和相关的软骨发育不良，这是由FGFR3的组成性活性突变引起的。为了了解FGF的生长抑制机制，我们分析了FGF2对软骨细胞中细胞周期调节分子的影响。FGF2显著抑制大鼠软骨肉瘤（RCS）细胞的增殖，并将其细胞周期阻滞在G(1)期。FGF2增加了与cyclin E-Cdk2复合物组装的RCS细胞中p21的表达，尽管cyclin E和Cdk2的表达均未增加。此外，以视网膜母细胞瘤蛋白（pRb）为底物评估的免疫沉淀细胞周期蛋白E或Cdk2的激酶活性被FGF-2显著降低。此外，FGF2在RCS细胞中将pRb转移到其低磷酸化的活性形式。FGF2不仅诱导体外培养的小鼠胎肢增殖软骨细胞中p21蛋白的表达，而且通过组蛋白H4 mRNA （S期细胞的标志）的表达来评估其增殖能力。此外，与野生型肢体相比，FGF2对p21缺失肢体软骨细胞增殖的抑制作用在体外部分减弱。综上所述，FGF对软骨细胞的生长抑制作用似乎至少部分是通过p21诱导和随后的细胞周期蛋白E-Cdk2失活和pRb激活介导的。
Fibroblast growth factor (FGF) and its receptor (FGFR) are thought to be negative regulators of chondrocytic growth, as exemplified by achondroplasia and related chondrodysplasias, which are caused by constitutively active mutations in FGFR3. To understand the growth-inhibitory mechanisms of FGF, we analyzed the effects of FGF2 on cell cycle-regulating molecules in chondrocytes. FGF2 dramatically inhibited proliferation of rat chondrosarcoma (RCS) cells and arrested their cell cycle at the G(1) phase. FGF2 increased p21 expression in RCS cells, which assembled with the cyclin E-Cdk2 complexes, although the expression of neither cyclin E nor Cdk2 increased. In addition, the kinase activity of immunoprecipitated cyclin E or Cdk2, assessed with retinoblastoma protein (pRb) as substrate, was dramatically reduced by FGF-2. Moreover, FGF2 shifted pRb to its underphosphorylated, active form in RCS cells. FGF2 not only induced p21 protein expression in proliferating chondrocytes in mouse fetal limbs cultured in vitro but also decreased their proliferation as assessed by the expression of histone H4 mRNA, a marker for cells in S phase. Furthermore, inhibitory effects of FGF2 on chondrocytic proliferation were partially reduced in p21-null limbs, compared with those in wild-type limbs in vitro. Taken together, FGF's growth inhibitory effects of chondrocytes appear to be mediated at least partially through p21 induction and the subsequent inactivation of cyclin E-Cdk2 and activation of pRb.