G-Protein Coupled Receptor Kinase-2 on IgE Signaling in Mast Cells

描述(申请人提供)：在美国，过敏性疾病是所有年龄段的疾病和残疾的主要原因之一。食物过敏影响了大约6%到8%的四岁以下儿童，超过3.7%的美国成年人。美国有2300多万人患有哮喘。它每年造成约50万人住院，2005年造成3384人死亡，每年的经济成本约为200亿美元。过去30年的密集研究增加了我们对哮喘和其他过敏性疾病的发病机制的了解。这些疾病是由对变应原过度热衷的Th2免疫反应引起的，其中免疫球蛋白E(IgE)和肥大细胞起着关键作用。因此，变应原对肥大细胞的高亲和力IgE受体(Fc5RI)的聚集导致组胺的快速释放以及脂质和细胞因子的产生，这与变态反应性疾病的表现有关。本研究的重点是研究肥大细胞中G蛋白偶联受体(GPCR)信号转导途径。人们普遍认为，激动剂诱导的一个或多个G蛋白偶联受体激酶(GRKs)诱导的GPCR磷酸化是导致受体脱敏的原因。出乎意料的是，我们发现沉默人类肥大细胞中GRK2的表达实质上抑制了Fc5RI介导的脱颗粒。基于这一发现，我们推测GRK2通过促进肥大细胞中的Fc5RI信号在变态反应性疾病中发挥新的作用。在目标1中，我们将在体外培养出沉默或过表达GRK2的小鼠骨髓来源的肥大细胞(BMMC)。在目标2中，我们将使用肥大细胞“敲入”方法来产生肥大细胞特异性沉默/过表达GRK2的小鼠。被动全身过敏反应(PSA)、小鼠肺切片支气管收缩和过敏性哮喘小鼠模型将被用来验证肥大细胞特异性表达GRK2是体内过敏反应所必需的假说。如果拟议的研究结果得以实现，可能会为食物过敏、过敏反应、鼻炎和哮喘等过敏性疾病的治疗提供新的方法。

DESCRIPTION (provided by applicant): Allergic diseases are among the major causes of illness and disability for all ages in the United States. Food allergy affects about 6% to 8% of children under the age of four, and more than 3.7% of adults in the U.S. More than 23 million people in the United States have asthma. It accounts for ~500,000 hospitalizations each year, was responsible for 3,384 deaths in 2005 and has an annual economic cost of ~$20b. Intense research over the past 30 years has increased our understanding of the pathogenesis of asthma and other allergic diseases. These diseases are caused by an overzealous Th2 immune response to allergens in which immunoglobulin E (IgE) and mast cells play critical roles. Thus, aggregation of high affinity IgE receptor (Fc5RI) by allergen on mast cells results in rapid histamine release and the generation of lipids and cytokines, which are responsible for the manifestations of allergic diseases. The focus of our research has been to study G protein coupled receptor (GPCR) signaling in mast cells. It is generally accepted that agonist-induced GPCR phosphorylation by one or more of the G protein coupled receptor kinases (GRKs) is responsible for receptor desensitization. Unexpectedly, we found that silencing GRK2 expression in human mast cells substantially inhibits Fc5RI-mediated degranulation. Based on this finding, we hypothesize that GRK2 plays a novel role in allergic diseases by promoting Fc5RI signaling in mast cells. In aim #1, we will generate murine bone marrow-derived mast cells (BMMC) with silencing or overexpression of GRK2 in vitro. In aim #2, we will use mast cell "knock-in" approach to generate mice with mast cell-specific silencing/overexpression of GRK2. Passive systemic anaphylaxis (PSA), bronchoconstriction in precision cut murine lung slices and murine model of allergic asthma will be used to test the hypothesis that mast cell-specific expression of GRK2 is required for allergic responses in vivo. If the outcome of the proposed studies are realized it may provide novel approaches for the treatment of allergic diseases such as food allergy, anaphylaxis, rhinitis and asthma.