Mechanisms of IgE mediated FceRI regulation

IgE 介导的 FceRI 调节机制

• 批准号: 6666455
• 负责人: JEAN-PIERRE M KINET
• 金额: $ 48.71万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6666455
• 关键词: antibody receptor; genetic polymorphism; immunogenetics; immunoglobulin E; immunoglobulin genes; immunoglobulin structure; immunoregulation; laboratory mouse; nuclear magnetic resonance spectroscopy; protein sequence; protein structure function; receptor expression; structural biology

(Applicant?s Abstract) The IgE/FceRI network is central to allergic inflammation and as such may be involved in the genesis of bronchial hyperresponsiveness and asthma. The level of FceRI surface expression is controlled by the level of circulating IgE. This regulation has great physiological significance since increased FceRI expression translates into enhanced effector function. Furthermore, recent anti-IgE clinical trails have underscored the importance of this regulation, showing decreased basophil effector function with corresponding decreased FceRI expression. However, nothing is known of how IgE regulates FceRI expression. We propose to further the understanding of IgE-mediated FceRI regulation through the four following aims. Specific Aim 1: Characterize the process of IgE-mediated FceRI up-regulation. In this aim we will dissect the process of IgE-mediated up-regulation of FceRI, determining the mechanism(s) involved. Specific Aim 2: Elucidate the impact of classical beta on IgE-mediated up-regulation of FceRL In this aim, we will follow-up on our preliminary data that show IgE-mediated up-regulation of FceRI is significantly greater in alphagamma2 than in alpha beta gamma2 expressing cells in vitro. We will determine the molecular mechanism(s) that underlie this difference. We will also analyze the physiolgical significance of alphagamma2 vs. alphabetagamma2 up-regulation in mice. Finally, we will determine whether known polymorphisms in the beta gene have an impact on IgE-mediated FceRI up-regulation. Specific Aim 3: Elucidate the impact of a new product of the beta gene on IgE-mediated up-regulation of FceRL Our preliminary data show that the human beta gene gives rise to two alternative transcripts that are co-expressed and encode two proteins with opposing functions: classical beta, and a newly described truncated protein, betaT. We will determine if betaT impacts IgE- mediated regulation. We will also assess if the alternative splicing to produce betaT is affected by the IgE-mediated regulation. Finally, we will ascertain whether known polymorphisms in the beta gene affect the alternative splicing of beta. Specific Aim 4: Dissect the minimal structure of FceRI required for IgE-mediated regulation. Having identified the molecular mechanism(s) that underlie IgE-mediated regulation of FcERI, we will determine the minimal structural basis for these mechanisms. We will identify the amino acid sequences in the alpha chain that are necessary to mediate up-regulation by using a number of mutated and chimeric receptors. In addition, we will determine if gamma impacts up-regulation utilizing a similar strategy. Finally, we will verify that the critical domains required for up-regulation affect the mechanism(s) of IgE-mediated FceRI up-regulation revealed in Aim 1. Taken together, these analyses will provide significant insights into the process and molecular parameters that control the IgE-mediated regulation of FceRI expression.

（申请人摘要）IgE/FceRI 网络是过敏的核心 炎症等可能参与支气管炎的发生 高反应性和哮喘。 FceRI表面表达水平为 受循环 IgE 水平控制。这个规定有很大 生理意义，因为增加的 FceRI 表达转化为 增强的效应器功能。此外，最近的抗 IgE 临床试验已 强调了这一调节的重要性，显示嗜碱性粒细胞减少 效应子功能相应降低 FceRI 表达。然而， 目前尚不清楚 IgE 如何调节 FceRI 表达。我们建议进一步 通过以下四个方面了解 IgE 介导的 FceRI 调节 目标。具体目标 1：表征 IgE 介导的 FceRI 上调过程。 为此，我们将剖析 IgE 介导的过程 FceRI 的上调，确定所涉及的机制。具体目标2： 阐明经典 β 对 IgE 介导的 FceRL 上调的影响 为实现这一目标，我们将跟进显示 IgE 介导的初步数据 αγ2 中 FceRI 的上调显着大于 α 体外表达βγ2的细胞。我们将确定分子 造成这种差异的机制。我们还将分析 alphagamma2 与 Alphagamma2 上调的生理意义 老鼠。最后，我们将确定β基因中是否存在已知的多态性 对 IgE 介导的 FceRI 上调有影响。具体目标 3：阐明 β基因的新产物对IgE介导的上调的影响 FceRL 我们的初步数据表明，人类β基因产生两种 共表达并编码两种蛋白质的替代转录本 相反的功能：经典的β和新描述的截短蛋白质， βT。我们将确定 betaT 是否影响 IgE 介导的调节。我们将 还评估产生 betaT 的选择性剪接是否受到 IgE 介导的调节。最后，我们将确定是否已知 β基因的多态性影响β的选择性剪接。 具体目标 4：剖析 FceRI 所需的最小结构 IgE 介导的调节。确定了分子机制 FcERI 是 IgE 介导的调节的基础，我们将确定最小 这些机制的结构基础。我们将鉴定氨基酸 α链中介导上调所必需的序列 使用许多突变和嵌合受体。此外，我们将 使用类似的策略确定伽马是否影响上调。 最后，我们将验证上调所需的关键域 影响目标 1 中揭示的 IgE 介导的 FceRI 上调机制。 总而言之，这些分析将为我们提供重要的见解 控制 IgE 介导的调节的过程和分子参数 FceRI 表达。