Pharmacological Study of G-proteins in Gene Regulation

G蛋白基因调控的药理学研究

• 批准号: 6874915
• 负责人: RICHARD D YE
• 金额: $ 26.04万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6874915
• 关键词: G protein; Kaposi' s sarcoma; arrestins; cell surface receptors; enzyme activity; gene induction /repression; genetically modified animals; laboratory mouse; nuclear factor kappa beta; phosphatidylinositol 3 kinase; phosphorylation; posttranslational modifications; protein protein interaction; protein tyrosine kinase; receptor coupling

DESCRIPTION (provided by applicant): Activation of numerous G-protein-coupled receptors (GPCRs) results in cell proliferation that contributes to the progression of diseases such as Kaposi's sarcoma. We have recently reported that GPCRs activate nuclear factor kappa B (NF-kappaB), which induces the expression of a large number of genes responsible for cell growth and survival. The NF-KappaB activation mechanims have been extensively characterized using model cytokines such as TNFalpha, but little is known about the G-protein pathways that activate this important transcription factor. Using pharmacological inhibitors and dominant negative DNA constructs that disrupt G-protein signaling, we have found that G-proteins vary in their ability to activate NF-KappaB. While many Galpha and Gbetagamma subunits mediate NF-KappaB activation, certain Galpha subunits can also inhibit NF-KappaB. Experiments are proposed in 3 specific aims to determine the mechanisms by which G-proteins regulate NFKappaB activation. In Aim 1, we will investigate the signaling pathways utilized by G13 for NF-KappaB activation. We hypothesize that signaling effectors downstream of the G13-p115RhoGEF-RhoA pathway play a critical role in NF-KappaB activation through p65 transactivation. Aim 2 is focused on Gbetagamma dimers in the differential activation of PI-3 kinases and Src protein tyrosine kinases, both leading to NF-KappaB activation but with different 1kappabetaalpha kinetics. We propose to identify the factors that determine the activation of these effectors of Gbetaalpha. The role of beta-arrestins in Gbetagamma-mediated NF-KappaB activation will also be examined. In Aim 3, we will determine how NF-KappaB activation is negatively regulated by G-proteins. A working hypothesis is that Galphai proteins have the opposite function of Gbetagamma in that they mediate inhibition of NF-KappaB activation in cells stimulated with proinflammatory agents. We will investigate a possible role of Galphai2 in suppression of NF-KappaB. A potential link to Galkphai-mediated inhibition of Raf-1 pathway will be examined. Collectively, these studies are expected to reveal how G-protein mediated proximal signaling events lead to different cytoplasmic and nuclear signaling and transcriptional regulation, and to identify potential sites for therapeutic intervention.

描述（由申请人提供）：大量G蛋白偶联受体（GPCR）的激活导致细胞增殖，从而导致卡波西肉瘤等疾病的进展。我们最近报道，GPCR 激活核因子 kappa B (NF-kappaB)，从而诱导大量负责细胞生长和存活的基因的表达。 NF-KappaB 激活机制已使​​用 TNFα 等模型细胞因子进行了广泛的表征，但对于激活这一重要转录因子的 G 蛋白途径知之甚少。使用破坏 G 蛋白信号传导的药理学抑制剂和显性失活 DNA 结构，我们发现 G 蛋白激活 NF-KappaB 的能力各不相同。虽然许多 Galpha 和 Gbetagamma 亚基介导 NF-KappaB 激活，但某些 Galpha 亚基也可以抑制 NF-KappaB。实验提出了 3 个具体目标，以确定 G 蛋白调节 NFKappaB 激活的机制。在目标 1 中，我们将研究 G13 用于 NF-KappaB 激活的信号通路。我们假设 G13-p115RhoGEF-RhoA 通路下游的信号传导效应器通过 p65 反式激活在 NF-KappaB 激活中发挥关键作用。目标 2 重点关注 PI-3 激酶和 Src 蛋白酪氨酸激酶差异激活中的 Gbetagamma 二聚体，两者都会导致 NF-KappaB 激活，但具有不同的 1kappabetaalpha 动力学。我们建议确定决定这些 Gbetaalpha 效应器激活的因素。还将检查 β-arrestins 在 Gbetagamma 介导的 NF-KappaB 激活中的作用。在目标 3 中，我们将确定 G 蛋白如何负向调节 NF-KappaB 激活。一个可行的假设是，Galphai 蛋白具有与 Gbetagamma 相反的功能，因为它们介导对促炎剂刺激的细胞中 NF-KappaB 激活的抑制。我们将研究 Galphai2 在抑制 NF-KappaB 中的可能作用。将检查与 Galkphai 介导的 Raf-1 通路抑制的潜在联系。总的来说，这些研究有望揭示 G 蛋白介导的近端信号传导事件如何导致不同的细胞质和核信号传导以及转录调控，并确定治疗干预的潜在位点。