Identification of the functional components of the Ras signaling pathway regulating pituitary cell-specific gene expression
Identification of the functional components of the Ras signaling pathway regulating pituitary cell-specific gene expression
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调节垂体细胞特异性基因表达的 Ras 信号通路功能成分的鉴定
DOI：
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发表时间：
1994
影响因子：
5.3
通讯作者：
A. Gutierrez
中科院分区：
文献类型：
--
作者：
Kerry E. Conrad;J. M. Oberwetter;R. Vaillancourt;Gary L. Johnson;A. Gutierrez
Ras是一种小的GTP结合蛋白，是功能性受体酪氨酸激酶信号传导所必需的。最终，Ras改变特定核转录因子的活性并调节新的基因表达模式。使用大鼠催乳素启动子构建在瞬时转染实验中，我们表明，致癌Ras和激活形式的Raf-1激酶选择性刺激细胞大鼠催乳素启动子在GH4大鼠垂体细胞。我们还表明，Ras信号完全被编码显性负Raf激酶的表达载体阻断。此外，使用分子遗传学方法，我们确定，抑制形式的p42丝裂原活化蛋白激酶和Ets-2转录因子干扰的Ras和Raf激活的大鼠催乳素启动子。这些发现定义了这些信号成分在催乳素基因激活中的功能要求，催乳素基因是一种细胞特异性基因，标志着催乳素垂体细胞类型。此外，这种分析使我们能够将Ras信号通路中的组分排序为Ras->Raf激酶->丝裂原活化蛋白激酶->Ets，因为它影响催乳素基因转录的调节。相比之下，我们表明，完整的c-Jun表达抑制了Ras诱导的催乳素启动子的激活，将其定义为该途径的负调节因子，而c-Jun能够增强GH4细胞中AP-1驱动的启动子的Ras激活。这些数据表明，c-Jun不是Ras信号的核介质，高度专业化，垂体细胞特异性催乳素细胞启动子。因此，我们已经定义了一个模型系统，它提供了一个理想的范式研究Ras/Raf信号通路及其对神经内分泌细胞特异性基因调控的影响。
Ras, a small GTP-binding protein, is required for functional receptor tyrosine kinase signaling. Ultimately, Ras alters the activity of specific nuclear transcription factors and regulates novel patterns of gene expression. Using a rat prolactin promoter construct in transient transfection experiments, we show that both oncogenic Ras and activated forms of Raf-1 kinase selectively stimulated the cellular rat prolactin promoter in GH4 rat pituitary cells. We also show that the Ras signal is completely blocked by an expression vector encoding a dominant-negative Raf kinase. Additionally, using a molecular genetic approach, we determined that inhibitory forms of p42 mitogen-activated protein kinase and an Ets-2 transcription factor interfere with both the Ras and the Raf activation of the rat prolactin promoter. These findings define a functional requirement for these signaling constituents in the activation of the prolactin gene, a cell-specific gene which marks the lactotroph pituitary cell type. Further, this analysis allowed us to order the components in the Ras signaling pathway as it impinges on regulation of prolactin gene transcription as Ras-->Raf kinase-->mitogen-activated protein kinase-->Ets. In contrast, we show that intact c-Jun expression inhibited the Ras-induced activation of the prolactin promoter, defining it as a negative regulator of this pathway, whereas c-Jun was able to enhance the Ras activation of an AP-1-driven promoter in GH4 cells. These data show that c-Jun is not the nuclear mediator of the Ras signal for the highly specialized, pituitary cell-specific prolactin cellular promoter. Thus, we have defined a model system which provides an ideal paradigm for studying Ras/Raf signaling pathways and their effects on neuroendocrine cell-specific gene regulation.
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DOI：
10.1073/pnas.90.21.10300
发表时间：
1993-11-01
影响因子：
11.1
作者：
GRAVES, LM;BORNFELDT, KE;KREBS, EG
通讯作者：
KREBS, EG
影响因子：
56.9
作者：
MOODIE, SA;WILLUMSEN, BM;WOLFMAN, A
通讯作者：
WOLFMAN, A
GH3 垂体无细胞提取物对大鼠催乳素基因的选择性转录和 DNase I 保护。
DOI：
10.1073/pnas.84.15.5211
发表时间：
1987
影响因子：
11.1
作者：
Gutierrez-Hartmann,A;Siddiqui,S;Loukin,S
通讯作者：
Loukin,S
影响因子：
16.6
作者：
M. Barbacid
通讯作者：
M. Barbacid
响应 ras 和 fms 信号通路的增强子元件由两个不同的核因子结合位点组成。
DOI：
10.1210/mend.6.7.1324418
发表时间：
1992
期刊：
Molecular endocrinology (Baltimore, Md.)
影响因子：
--
作者：
Reddy,MA;Langer,SJ;Colman,MS;Ostrowski,MC
通讯作者：
Ostrowski,MC