Novel Roles of GRK2 and beta-arrestin2 on mast cell-mediated allergy and Inflammation

摘要： 肥大细胞(MC)通过细胞表面Ig E受体(FcεRI)的聚集而激活，导致生命- 严重的疾病，如过敏反应和哮喘。MC生物学最近令人振奋的发展是 发现它们表达一种新的G蛋白偶联受体(GPCR)，称为MRGPRX2(小鼠 与之对应的MRGPRB2)，这导致了越来越多的疾病，如假过敏、神经源性 炎症，非组胺能瘙痒，过敏性接触性皮炎和特应性皮炎。的主要目标是 这项建议是通过靶向新的信号通路来调节FcεRI和mRgprB2介导的反应 MCS。 在它们被激活后，大多数gpcr通过gpcr的磷酸化来进行脱敏。 激酶(GRK)和连接蛋白β-ARRs(β-ARRs)的募集。我们写了四部小说 这些观察结果为这一提议提供了基础。首先，我们发现，与大多数GPCR不同，MRGPRX2是 抵抗GRK2介导的脱敏，但有助于IgE介导的MC脱颗粒和细胞因子 制作。第二，β-arr2通过修饰未知基因抑制IgE和mrgprB2介导的MC脱颗粒。 钙离子动员的下游组分。第三，β-arr2在体外促进MC趋化和过敏。 活体接触性皮炎。第四，β-ARR2对MC趋化的影响与Ser3有关 肌动蛋白解聚因子cofilin的去磷酸化。蛋白激酶Cβ(PKCβ)的激活 促进MC脱颗粒，PKCα磷酸化Ser23和Ser24处的Cofilin以增加肌动蛋白聚合， 导致脱颗粒停止。基于这些发现，我们假设GRK2促进IgE- MCs通过调节Syk/Akt/NF-κB信号而介导的反应，而β-Arr2同时调节Fc、εRI和 MRgprB2通过作为支架蛋白对cofilin进行磷酸化和去磷酸化来应答。 在目标1中，我们将确定GRK2在FcεRI介导的MC脱颗粒和细胞因子产生中的作用。 体外和体内过敏反应。在目标2中，我们将确定β-ARR2在FcεRI和MRGprB2-上的作用 体外反应和体内炎症反应。这项研究的完成可能会提供更好的理由 用于MC介导性疾病的新疗法的开发。

Summary: Mast cell (MC) activation through the aggregation of cell surface IgE receptors (FcεRI) leads to life- threatening conditions such as anaphylaxis and asthma. Recent exciting development in MC biology has been the discovery that they express a novel G protein coupled receptor (GPCR) known as MRGPRX2 (mouse counterpart MrgprB2), which contributes to a growing list of conditions such as pseudoallergy, neurogenic inflammation, non-histaminergic itch, allergic contact dermatitis and atopic dermatitis. The main objective of this proposal is to modulate FcεRI and MrgprB2-mediated responses by targeting novel signaling pathways in MCs. Following their activation, most GPCRs undergo desensitization via their phosphorylation by GPCR kinases (GRKs) and the recruitment of the adapter proteins, β-arrestins (β-arrs). We made four novel observations, which provide the basis of this proposal. First, we found that unlike most GPCRs, MRGPRX2 is resistant to GRK2-mediated desensitization but it contributes to IgE-mediated MC degranulation and cytokine production. Second, β-arr2 inhibits both IgE and MrgprB2-mediated MC degranulation by modifying unknown components downstream of Ca2+ mobilization. Third, β-arr2 contributes to MC chemotaxis in vitro and allergic contact dermatitis in vivo. Fourth, the effect of β-arr2 on MC chemotaxis is associated with Ser3 dephosphorylation of the actin depolymerization factor cofilin. While activation of protein kinase Cβ (PKCβ) promotes MC degranulation, PKCα phosphorylates cofilin at Ser23 and Ser24 to increase actin polymerization, resulting in cessation of degranulation. Based on these findings, we hypothesize that GRK2 promotes IgE- mediated responses in MCs via the regulation of Syk/Akt/NF-κB signaling but β-arr2 modulates both FcεRI and MrgprB2 responses by functioning as a scaffolding protein for phosphorylation and dephosphorylation of cofilin. In aim 1, we will determine the role of GRK2 on FcεRI-mediated MC degranulation and cytokine generation in vitro and allergic response in vivo. In aim 2, we will determine the role of β-arr2 on FcεRI and MrgprB2- resposnes in vitro and inflammatory responses in vivo. Completion of this study may provide better rationale for the development of novel therapeutics for the MC-mediated disorders.