Signaling Mechanisms Regulating Pituitary Gene Expression

调节垂体基因表达的信号机制

• 批准号: 7912895
• 负责人: DAWN L DUVAL
• 金额: $ 29.11万
• 依托单位: COLORADO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-10 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7912895
• 关键词: Affinity; Anterior Pituitary Gland; Binding; Binding Sites; Cell Cycle; Cell Cycle Progression; Cell Line; Cell Proliferation; Cell model; Cells; Code; Cyclic AMP-Dependent Protein Kinases; DNA Binding; Development; Disease; Estradiol; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Goals; Growth; Hormonal; In Vitro; Mediating; Molecular Conformation; Mutation; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Pituitary Gland; Pituitary Hormones; Prolactin; Proteins; Role; Serine; Serine/Threonine Phosphorylation; Signal Pathway; Signal Transduction; Site; Solutions; Threonine; Threonine Phosphorylation Site; Transcriptional Regulation; beta Subunit Thyrotropin; cell growth; cell type; combinatorial; homeodomain; in vivo; lactotroph; monomer; mutant; peptide hormone; pituitary gland development; promoter; protein protein interaction; transcription factor; transcription factor Pit-1

Pit-1/GHF-1 governs the ontogeny of three distinct pituitary cell types, somatotrophs, lactotrophs, and thyrotrophs. Since all three pituitary cell types express Pit-1, but each expresses a distinct pituitary hormone, factors in addition to Pit-1 must be required for cell-specific expression of GH, PRL, and TSH beta. To accomplish this, Pit-1 establishes a number of combinatorial codes that govern the cell-type specific transcriptional regulation of these hormonal marker genes. These codes can involve both synergistic or inhibitory protein-protein interactions between Pit-1 and other transcription factors. In addition, two functional serine/threonine phosphorylation sites have been identified in Pit-1: Serine 115 and Threonine 220. Both in vivo and in vitro studies have shown that these sites can be targeted by Protein Kinases A and C, as well as cell cycle dependent kinases. One of these sites, T220, is highly conserved among homeodomain transcription factors. Unfortunately, the functional role of phosphorylation of these sites in Pit-1 remains unclear. Mutations of Pit-1 which mimic the phosphorylation of threonine 220, T220D and T220E, reduced the ability of Pit-1 to target Ras and estradiol stimulation to the prolactin promoter. This impaired signaling capability correlated with an inability of the T220D Pit-1 mutant to bind to sites in the prolactin promoter as a monomer. Finally, the established role of Pit-1 in pituitary cell proliferation, as well as the correlation of Pit-1 phosphorylation with cell cycle progression, suggests that the phosphorylation of Pit-1 may serve as a regulatory switch between cell proliferation and differentiation in the Pit-1 lineages. Unifying hypothesis: Phosphorylation of Pit-1 induces structural changes that alter its affinity for distinct DNA binding sites and protein partners. These changes regulate Pit-1¿s ability to respond to specific signaling pathways that mediate growth and cell-specific gene transcription. Overall Goal: The overall goal of this proposal is to determine the physiological effects of, and mechanisms by which, phosphorylation of Pit-1 regulates transcription and proliferation of cells in the Pit-1 lineage. We will use in vitro cell models to determine 1) the effect of Pit-1 phosphorylation on cell cycle progression, 2) the cellular and developmental conditions which induce phosphorylation of Pit-1, 3) changes in Pit-1 structural conformations upon phosphorylation, 4) and the effect of phosphorylation on the ability of Pit-1 to integrate cell specific signaling to its primary target gene promoters in the pituitary. These results will be correlated with changes in cell growth and gene expression in vivo.

Pit-1/GHF-1控制三种不同垂体细胞类型的个体发育，即生长激素细胞、催乳激素细胞和 促甲状腺激素细胞由于所有三种垂体细胞类型都表达Pit-1，但每种都表达不同的垂体激素， 除Pit-1外，细胞特异性表达GH、PRL和TSH β还必须需要其他因子。到 为了实现这一点，Pit-1建立了许多控制细胞类型特异性的组合代码， 这些激素标记基因的转录调控。这些代码可以涉及协同或 抑制Pit-1与其他转录因子之间的蛋白质-蛋白质相互作用。此外，两个功能 丝氨酸/苏氨酸磷酸化位点已在Pit-1中鉴定：丝氨酸115和苏氨酸220。无论是在 体内和体外研究表明，这些位点可以被蛋白激酶A和C靶向， 细胞周期依赖性激酶。这些位点之一，T220，在同源结构域转录中高度保守 因素不幸的是，Pit-1中这些位点磷酸化的功能作用仍不清楚。突变 模拟苏氨酸220、T220 D和T220 E磷酸化的Pit-1的磷酸化，降低了Pit-1的能力， 靶向Ras和雌二醇刺激催乳素启动子。这种受损的信号传导能力与 T220 D Pit-1突变体不能作为单体与催乳素启动子中的位点结合。最后 Pit-1在垂体细胞增殖中的作用，以及Pit-1磷酸化与细胞增殖的相关性。 周期进展，表明Pit-1的磷酸化可能作为细胞之间的调节开关， Pit-1谱系中的增殖和分化。 统一假设：Pit-1的磷酸化诱导结构变化，改变其对不同DNA的亲和力 结合位点和蛋白质伴侣。这些变化调节Pit-1对特定信号的反应能力 介导生长和细胞特异性基因转录的途径。 总体目标：本提案的总体目标是通过以下方式确定生理效应和机制： Pit-1的磷酸化调节Pit-1谱系中细胞的转录和增殖。 我们将使用体外细胞模型来确定1）Pit-1磷酸化对细胞周期进程的影响，2） 诱导Pit-1磷酸化的细胞和发育条件，3）Pit-1结构的变化 4）以及磷酸化对Pit-1整合细胞的能力的影响 特异性信号传导至垂体中的主要靶基因启动子。这些结果将与 体内细胞生长和基因表达的变化。

项目成果

Transcription factor Ets1 cooperates with estrogen receptor α to stimulate estradiol-dependent growth in breast cancer cells and tumors.

• DOI: 10.1371/journal.pone.0068815
• 发表时间: 2013
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Kalet BT;Anglin SR;Handschy A;O'Donoghue LE;Halsey C;Chubb L;Korch C;Duval DL
• 通讯作者: Duval DL