In vivo regulation of growth hormone-stimulated gene transcription by STAT5b.
In vivo regulation of growth hormone-stimulated gene transcription by STAT5b.
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DOI：
10.1152/ajpendo.00389.2003
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
J. Woelfle;P. Rotwein
中科院分区：
文献类型：
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作者：
J. Woelfle;P. Rotwein
生长激素（GH）的长期效应是通过基因表达的协调变化介导的，这些变化是激素激活的信号转导途径和特定反馈回路之间相互作用的结果。最近在小鼠中的研究表明，转录因子STAT 5 b是GH调节的体细胞生长途径的一部分，因为缺乏这种蛋白质的小鼠表现出生长速率降低。为了评估Stat 5 b在GH刺激的基因表达中的作用，我们通过定量腺病毒介导的基因转移将该蛋白质的修饰版本递送到垂体缺陷雄性大鼠的肝脏。在细胞培养的初步研究中，组成型活性和显性负性STAT 5 b都显示出对特定DNA反应元件的适当结合特性。在体内表达后，这两种蛋白质都不能阻止STATs 1和3在肝脏中的核积累。显性负性STAT 5 b完全抑制GH刺激的编码生长促进蛋白IGF-I、IGF结合蛋白-3（IGFBP-3）和酸不稳定亚基（ALS）的基因转录，这些基因包含主要的循环IGF-I复合物，并阻断GH抑制剂SOCS-1、SOCS-2和CIS的表达，但对SOCS-3的诱导几乎没有影响。组成型活性STAT 5 b在没有激素的情况下刺激IGF-I、ALS和IGFBP-3的稳健转录，但对修饰GH介导的SOCS家族基因的激活作用不大。编码EGFP的腺病毒没有作用。这些结果，除了建立STAT 5 b作为GH刺激的基因转录的关键代理之一，证明了使用体内基因转移的目标和解剖复杂的腺苷酸激活的信号转导通路的不同组件的功能的可行性。
The long-term effects of growth hormone (GH) are mediated through coordinated changes in gene expression that are the outcome of interactions between hormone-activated signal transduction pathways and specific feedback loops. Recent studies in mice have implicated the transcription factor STAT5b as part of the GH-regulated somatic growth pathway, because mice lacking this protein showed diminished growth rates. To assess the role of Stat5b in GH-stimulated gene expression, we have delivered modified versions of the protein to the liver of pituitary-deficient male rats by quantitative adenovirus-mediated gene transfer. In pilot studies in cell culture, both constitutive-active and dominant-negative STAT5b showed appropriate binding properties toward a specific DNA response element. After in vivo expression, neither protein prevented nuclear accumulation of STATs 1 and 3 in the liver. Dominant-negative STAT5b completely inhibited GH-stimulated transcription of genes encoding the growth-promoting proteins IGF-I, IGF-binding protein-3 (IGFBP-3), and acid-labile subunit (ALS), which comprise the major circulating IGF-I complex, and blocked expression of the GH inhibitors SOCS-1, SOCS-2, and CIS, but had little effect on induction of SOCS-3. Constitutive-active STAT5b stimulated robust transcription of IGF-I, ALS, and IGFBP-3 in the absence of hormone but did little to modify GH-mediated activation of SOCS family genes. An adenovirus encoding EGFP was without effect. These results, in addition to establishing STAT5b as one of the key agents of GH-stimulated gene transcription, demonstrate the feasibility of using in vivo gene transfer to target and dissect the functions of distinct components of complex hormone-activated signal transduction pathways.