17β-estradiol-dependent activation of signal transducer and activator of transcription-1 in human fetal osteoblasts is dependent on Src kinase activity
17β-estradiol-dependent activation of signal transducer and activator of transcription-1 in human fetal osteoblasts is dependent on Src kinase activity
复制标题
DOI：
10.1210/en.2004-0486
复制
发表时间：
2005-01-01
期刊：
影响因子：
4.8
通讯作者：
Maran, A
中科院分区：
文献类型：
--
作者：
Kennedy, AM;Shogren, KL;Maran, A
雌激素对骨骼的正常生长和重塑是必不可少的。虽然雌激素对骨细胞的作用机制已经得到了广泛的研究，但雌激素激活的信号转导通路的全谱还不清楚。在本报告中，我们研究了性腺激素17β-雌二醇对缺乏经典雌激素受体(ER)的培养的人胎儿成骨细胞信号转导和转录激活因子-1(STAT1)蛋白的调节作用。17β-雌二醇(10 NM)可引起STAT1蛋白的快速(15分钟内)活化，表现为酪氨酸磷酸化和DNA结合活性增加。此外，在瞬时转基因实验中，17β-雌二醇增加了伽马激活序列依赖的转录，这表明Stat蛋白依赖的转录增加。在瞬时表达显性-负性STAT1突变蛋白的细胞中，雌激素依赖的STAT1激活被阻断。ER拮抗剂ICI182,780不能抑制17β-雌二醇对STAT1的激活，进一步证明它不依赖经典的ER。17β-雌二醇诱导ER阴性乳腺癌细胞中STAT1的快速(15分钟内)磷酸化，并刺激伽马激活的序列依赖转录，表明这些结果并不是骨细胞所特有的。在雌激素处理的细胞中，参与STAT1磷酸化和激活的快速雌激素效应被Src家族激酶抑制剂PP2阻断；在雌激素处理的细胞中，激活的STAT1与Src蛋白相关。这些发现表明，在雌激素介导的STAT1激活过程中需要Src激酶通路。因此，17β-雌二醇处理的成骨细胞和乳腺癌细胞中STAT1的ER非依赖性激活可能部分介导了雌激素对靶细胞的作用。
Estrogen is essential for normal growth and remodeling of bone. Although the mechanism of estrogen action on bone cells has been widely investigated, the full spectrum of signal transduction pathways activated by estrogen is unknown. In this report, we investigate the effects of the gonadal hormone 17beta-estradiol on the regulation of signal transducer and activator of transcription-1 (Stat1) protein in cultured human fetal osteoblast cells, devoid of the classical estrogen receptors (ERs). 17beta-Estradiol ( 10 nM) led to rapid ( within 15 min) activation of Stat1 protein as indicated by increases in tyrosine phosphorylation and DNA binding activity. Also, 17beta-estradiol increased gamma-activated sequence-dependent transcription in transient transfection assays, suggesting an increase in Stat protein-dependent transcription. Estrogen-dependent Stat1 activation was blocked in cells that transiently express dominant-negative Stat1 mutant protein. Activation of Stat1 by 17beta-estradiol was not inhibited by ER antagonist ICI 182,780, providing further evidence that it is not dependent on classical ERs. 17beta-Estradiol induced rapid ( within 15 min) Stat1 phosphorylation and stimulated gamma-activated sequence-dependent transcription in ER-negative breast cancer cells, indicating that these results are not unique to bone cells. The rapid estrogenic effect involving the phosphorylation and activation of Stat1 was blocked in the presence of Src family kinase inhibitor PP2; activated Stat1 was associated with Src protein in estrogen-treated cells. These findings indicate the requirement for Src kinase pathways in estrogen-mediated Stat1 activation. Thus, the ER-independent activation of Stat1 in 17beta-estradiol-treated osteoblast and breast cancer cells may partially mediate the actions of estrogen on target cells.