Ligand-dependent, Pit-1/growth hormone factor-1 (GHF-1)-independent transcriptional stimulation of rat growth hormone gene expression by thyroid hormone receptors in vitro
Ligand-dependent, Pit-1/growth hormone factor-1 (GHF-1)-independent transcriptional stimulation of rat growth hormone gene expression by thyroid hormone receptors in vitro
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体外甲状腺激素受体对大鼠生长激素基因表达的配体依赖性、Pit-1/生长激素因子-1 (GHF-1) 独立转录刺激
DOI：
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发表时间：
1993
影响因子：
5.3
通讯作者：
W. W. Chin
中科院分区：
文献类型：
--
作者：
Chen;W. W. Chin
大鼠生长激素(RGH)基因在垂体前叶的表达受垂体特异性转录因子Pit-1/GHF-1和其他分布更广泛的因子如甲状腺激素受体(TRs)、Sp1和糖皮质激素受体的调节。甲状腺激素(T3)介导的RGH基因表达的转录刺激在体内和体外都得到了广泛的研究，包括：(1)RGH基因转录的印迹杂交；(2)核连续检测RGH基因的转录速率；(3)报告基因的表达：将RGH基因5‘侧翼序列与报告基因相连的嵌合质粒稳定或瞬时地转入垂体和/或非垂体细胞。这些研究表明，Pit-1/GHF-1结合位点是充分发挥T3作用所必需的。我们建立了一个无细胞体外转录系统，以进一步研究TRS和Pit-1/GHF-1在RGH基因激活中的作用。以GH3核提取液作为TRs和Pit-1/GHF-1的来源，体外转录实验表明，T3对RGH启动子活性的刺激依赖于在GH3核提取液中添加T3。这种转录刺激随着配体浓度的增加而增强，并且是T3特异性的，而不是T4或相反的T3。核提取物与RGH-甲状腺激素反应元件(-200~-160)预孵育后，可完全消除T3对RGH启动子活性的刺激作用，但与Pit-1/GHF-1(-137~-65)寡核苷酸预孵育则不能。此外，Pit-1/GHF-1结合位点的缺失和RGH启动子近端Pit-1/GHF-1结合位点的突变都不能消除T3效应。这些结果证明，T3刺激的RGH启动子活性不依赖于Pit-1/GHF-1，并提出了T3刺激RGH基因表达的可能性可能涉及TRS与一般转录装置的直接相互作用。
The expression of the rat growth hormone (rGH) gene in the anterior pituitary gland is modulated by Pit-1/GHF-1, a pituitary-specific transcription factor, and by other more widely distributed factors, such as the thyroid hormone receptors (TRs), Sp1, and the glucocorticoid receptor. Thyroid hormone (T3)-mediated transcriptional stimulation of rGH gene expression has been extensively studied in vivo and in vitro including the measurements of (i) rGH mRNA by blot hybridization, (ii) transcriptional rate of rGH gene by nuclear run-on, and (iii) reporter gene expression in which a chimeric plasmid containing 5'-flanking sequences of the rGH gene linked to a reporter gene has been transfected either stably or transiently into pituitary and/or nonpituitary cells. From these studies, it has been suggested that the Pit-1/GHF-1 binding site is necessary for full T3 action. We developed a cell-free in vitro transcription system to examine further the roles of the TRs and Pit-1/GHF-1 in rGH gene activation. Using GH3 nuclear extract as a source of TRs and Pit-1/GHF-1, this in vitro transcription assay showed that T3 stimulation of rGH promoter activity is dependent on the addition of T3 to the GH3 nuclear extract. This transcriptional stimulation was augmented with increasing concentrations of ligand and was T3, but not T4 or reverse T3, specific. T3-mediated stimulation of rGH promoter activity was completely abolished by preincubation of the nuclear extract with rGH-thyroid hormone response element (-200 to -160) but not with Pit-1/GHF-1 (-137 to -65) oligonucleotides. Further, neither deletion of both Pit-1/GHF-1 binding sites nor mutation of the proximal Pit-1/GHF-1 binding site from the rGH promoter abrogated the T3 effect. These results provide evidence that T3-stimulated rGH promoter activity is independent of Pit-1/GHF-1 and raise the possibility that the stimulation of rGH gene expression by T3 might involve direct interaction of TRs with the general transcriptional apparatus.
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甲状腺激素控制大鼠垂体前叶细胞中促甲状腺素基因的表达。
影响因子：
4.8
作者：
Shupnik,MA;Ridgway,EC
通讯作者：
Ridgway,EC
3,5,3-三碘-L-甲状腺氨酸调节 GH1 细胞中甲状腺激素核受体水平。
DOI：
--
发表时间：
1981
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Raaka,BM;Samuels,HH
通讯作者：
Samuels,HH
鉴定增强甲状腺激素受体与甲状腺激素反应元件结合的核因子。
DOI：
10.1210/mend-3-9-1434
发表时间：
1989
期刊：
Molecular endocrinology (Baltimore, Md.)
影响因子：
--
作者：
Murray,MB;Towle,HC
通讯作者：
Towle,HC
含有同源盒的生长激素特异性转录因子 GHF-1 的纯化。
DOI：
10.1126/science.2563596
发表时间：
1989
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Castrillo,JL;Bodner,M;Karin,M
通讯作者：
Karin,M
DOI：
--
发表时间：
1984
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Yaffe,BM;Samuels,HH
通讯作者：
Samuels,HH