Signaling Diversity Among Gqa Family Members

体现 Gqa 家族成员的多样性

• 批准号: 6520320
• 负责人: JOHN R HEPLER
• 金额: $ 26.6万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-02 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6520320
• 关键词: G protein; acylation; biological signal transduction; cell differentiation; cell growth regulation; cysteine; gene expression; high performance liquid chromatography; intermolecular interaction; intracellular transport; mass spectrometry; microarray technology; palmitates; phospholipase C; posttranslational modifications; protein binding; protein isoforms; protein localization; protein purification; protein structure function; protein transport; radiotracer; reporter genes; site directed mutagenesis; tissue /cell culture; western blottings

Many hormones and neurotransmitters rely on the Gq class of heterotrimeric G proteins (Gq/11alpha, G14alpha, and G15/16alpha) to exert their actions at target issues. Gqalpha family members activate PLCbeta and inositol lipid signaling, and established models suggest that the cellular actions of these Galpha are identical and result from activation of Ca PKC pathways. However compelling evidence now indicated that Gq/11alpha, G14alpha, and G15/16alpha differ markedly in their overall cellular responses, their interactions with certain protein binding partners, and their cellular and biochemical properties. Contrary to established models, my working hypothesis is that Gq/11alpha, G14alpha and G15/16alpha regulate multiple overlapping and distinct signaling cascades, and are regulated differently by host cells to elicit a distinct profile of cellular responses. Consistent with this idea, Gqalph family members are expressed in different cells, and Gqalpha interacts with multiple signaling proteins besides PLCbeta, though the relative contribution of each binding partner to Gqalpha signaling is unknown. Furthermore, Gq/11alpha, G14alpha and G15/16alpha share only 57 percent overall amino acid identity, and just 12 percent identity within their first 35 residues (N- terminus) which contains fatty acids that are essential for regulating Galpha signaling capacity. Although the acylation state of G14alpha and G15/16alpha is unknown, sequence alignments predict that Gqalpha family members are modified differently. Using modem molecular, cellular, and biochemical approaches study G protein functions, the specific aims will be to: 1. Define biochemical modifications present on Gq/11alpha, G14alpha, and G15/16alpha important for regulating signaling functions. 2. Define factors that regulate Gq/11alpha, G14alpha and G15/16alpha signaling capacity including target subcelluar localization and interactions with protein binding partners. 3. Determine the diversity of cell signaling responses elicited by Gqalpha, G14alpha and G15/16alpha in selected cells, and the relative contribution of Galpha binding partners to those responses. Heterotrimeric G proteins serve essential roles in cell physiology by inking cell surface receptors to intracellular responses. G protein dysfunction is the direct cause of a growing list of human diseases, and the majority of currently available drugs exert their actions on G protein signaling pathways. These experiments will determine functional correlates for the biochemical differences observed among the Gqalpha family of G proteins, and offer new insights into the diversity and regulation of signaling responses elicited by these important G proteins. Information gained from these studies will help us to better understand G proteins as therapeutic targets.

许多激素和神经递质依赖于Gq类异三聚体G蛋白(Gq/11pha、G14pha和G15/16pha)在靶点问题上发挥作用。GqAlpha家族成员激活PLCbeta和肌醇脂质信号，已建立的模型表明这些Galpha的细胞作用是相同的，并且是激活Ca PKC通路的结果。然而，令人信服的证据表明，GQ/11α、G14α和G15/16α在总体细胞反应、与某些蛋白质结合伙伴的相互作用以及细胞和生化特性方面存在显著差异。与已建立的模型相反，我的工作假设是GQ/11α、G14α和G15/16α调节多个重叠和不同的信号级联，并由宿主细胞以不同的方式调节，以引发不同的细胞反应。与这一观点一致的是，Gqalph家族成员在不同的细胞中表达，GqAlpha除了与PLCβ相互作用外，还与多种信号蛋白相互作用，尽管每个结合伙伴对GqAlpha信号的相对贡献尚不清楚。此外，GQ/11pha、G14pha和G15/16pha只有57%的氨基酸同源性，在它们的前35个残基(N-端)中只有12%的同源性，这些残基含有调节Galpha信号传导能力所必需的脂肪酸。虽然G14α和G15/16α的酰化状态尚不清楚，但序列比对预测GqAlpha家族成员的修饰方式不同。利用现代分子、细胞和生化方法研究G蛋白的功能，其具体目的是：1.确定GQ/11α、G14α和G15/16α上存在的对调节信号功能重要的生化修饰。2.确定调节Gq/11pha、G14pha和G15/16pha信号转导能力的因子，包括靶细胞亚细胞定位和与蛋白结合伙伴的相互作用。3.确定Gqpha、G14α和G15/16α在所选细胞中引发的细胞信号反应的多样性，以及Galpha结合伙伴对这些反应的相对贡献。异三聚体G蛋白通过将细胞表面受体与细胞内反应联系起来，在细胞生理学中发挥重要作用。G蛋白功能障碍是越来越多的人类疾病的直接原因，目前可用的大多数药物都在G蛋白信号通路上发挥作用。这些实验将确定观察到的G蛋白Gqpha家族之间生化差异的功能相关性，并为这些重要的G蛋白引发的信号反应的多样性和调控提供新的见解。从这些研究中获得的信息将有助于我们更好地理解G蛋白作为治疗靶点。