Mechanism of IgE Mediated FceRI Regulation

描述（由申请方提供）：IgE通过以下方式介导过敏反应： 与免疫细胞上的特异性受体FceRI结合。基于多价 在抗原结合后，FceRI受体变得交联，从而引发 激活事件。FceRI细胞表面表达的水平由以下因素控制： IgE水平。这种调节具有重要的生理意义， 增加的FceRI表达转化为增强的FceRI效应子功能 表达细胞如肥大细胞和嗜碱性粒细胞。近期抗IgE临床 试验表明， 降低血清IgE导致FceRI表达降低和嗜碱性粒细胞减少 效应子功能这种IgE介导的FceRI表达的机制 监管还没有得到很好的描述，我们建议调查它 使用以下目标。目的1：研究IgE介导的FceRI的过程 上调我们将确定所涉及的机制。目标2：比较 FceRI的两种同种型ag（2）和abg（2）对该调节的影响。的 同种型由B链的存在或不存在来定义，所述b链是 FceRI表达和功能。我们将根据我们的初步数据采取后续行动， IgE介导的FceRI的上调在ag（2）中比在 体外表达ABG（2）的细胞。我们将确定分子机制（S） 这一差异的基础。我们将分析其生理意义 在小鼠中Ag（2）与ABG（2）调节的差异。我们将确定 B基因中已知的特应性相关多态性是否影响 IgE介导的FceRI调节。目标3：阐明新描述的 B基因产物对IgE介导的FceRI调节的影响。我们的初步数据 显示人类B基因产生两种选择性剪接的转录物 共表达并编码两种具有相反功能的蛋白质; 经典的，已经描述的B，和新描述的截短蛋白，bT。我们 将确定bT是否影响IgE介导的调节。我们还将评估， 产生bT的选择性剪接受这种IgE介导的 调控最后，我们将确定是否已知的原子性相关 B基因中的多态性影响B的可变剪接。目标4： 剖析IgE介导的调控所需的FceRI的最小结构。我们 将确定a链中的氨基酸序列， 使用类似的策略介导FceRI上调。最后我们将 验证由此确定的关键序列影响以下机制： IgE介导的FceRI上调显示在Aim 1中。综上所述各项 分析将提供重要的见解的过程和分子 这些参数控制IgE介导的FceRI表达调节。

DESCRIPTION (provided by the applicant): IgE mediates allergic responses by binding to a specific receptor, FceRI, on immune cells. Upon multivalent antigen binding, FceRI receptors become cross-linked, thus initiating activation events. The level of FceRI cell surface expression is controlled by IgE levels. This regulation has great physiological significance since increased FceRI expression translates into enhanced effector function of FceRI expressing cells such as mast cells and basophils. Recent anti-IgE clinical trials have underscored the importance of this regulation by showing that lowering serum IgE results in decreased FceRI expression and decreased basophil effector function. The mechanism of this IgE-mediated FceRI expression regulation has not been well characterized, and we propose to investigate it using the following aims. Aim l: Characterize the process of IgE-mediated FceRI up-regulation. We will determine the mechanism(s) involved. Aim 2: Compare the impact of the two isoforms of FceRI, ag(2) and abg(2) on this regulation. The isoforms are defined by the absence or presence of the b chain, an amplifier of FceRI expression and function. We will follow-up on our preliminary data that IgE-mediated up-regulation of FceRI is significantly greater in ag(2) than in abg(2) expressing cells in vitro. We will determine the molecular mechanism(s) that underlie this difference. We will analyze the physiological significance of this difference in regulation of ag(2) vs. abg(2) in mice. We will determine whether known atopy-associated polymorphisms in the b gene have an impact of IgE-mediated FceRI regulation. Aim 3: elucidate the impact of a newly described product of the b gene on IgE-mediated FceRI regulation. Our preliminary data show that the human b gene gives rise to two alternatively spliced transcripts that are co-expressed and encode two proteins with opposing functions; the classical, already described B, and a newly described truncated protein, bT. We will determine if bT impacts IgE-mediated regulation. We will also assess if the alternative splicing that produces bT is affected by this IgE-mediated regulation. Finally, we will ascertain whether known atopy-associated polymorphisms in the b gene affect the alternative splicing of b. Aim 4: Dissect the minimal structure of FceRI required for IgE-mediated regulation. We will identify the amino acid sequences in the a chain that are necessary to mediate FceRI up-regulation utilizing a similar strategy. Finally, we will verify that the critical sequences thus identified affect the mechanism(s) of IgE-mediated FceRI up-regulation revealed in Aim l. Taken together, these analyses will provide significant insights into the process and molecular parameters that control the IgE-mediated regulation of FceRI expression.