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

描述（由申请人提供）：过敏性疾病是美国所有年龄段的疾病和残疾的主要原因之一。食物过敏影响了约6%至8%的四岁以下儿童，超过3.7%的美国成年人。美国有超过2300万人患有哮喘。它每年约有50万人住院，2005年造成3,384人死亡，每年造成约200亿美元的经济损失。在过去的30年里，激烈的研究增加了我们对哮喘和其他过敏性疾病发病机制的理解。这些疾病是由对过敏原的过度Th2免疫反应引起的，其中免疫球蛋白E （IgE）和肥大细胞起关键作用。因此，过敏原在肥大细胞上聚集高亲和力IgE受体（Fc5RI），导致组胺快速释放，脂质和细胞因子的产生，这是过敏性疾病表现的原因。我们的研究重点是研究肥大细胞中G蛋白偶联受体（GPCR）信号转导。人们普遍认为，一种或多种G蛋白偶联受体激酶（GRKs）引起的激动剂诱导的GPCR磷酸化是受体脱敏的原因。出乎意料的是，我们发现在人肥大细胞中沉默GRK2表达可显著抑制fc5ri介导的脱颗粒。基于这一发现，我们假设GRK2通过促进肥大细胞中的Fc5RI信号传导在过敏性疾病中发挥新的作用。在目标1中，我们将在体外培养GRK2沉默或过表达的小鼠骨髓源性肥大细胞（BMMC）。在目标#2中，我们将使用肥大细胞“敲入”方法来产生具有肥大细胞特异性GRK2沉默/过表达的小鼠。我们将使用被动全身性过敏反应（PSA）、精确切割小鼠肺片支气管收缩和小鼠过敏性哮喘模型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设。如果这项研究的结果得以实现，它可能为食物过敏、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. PUBLIC HEALTH RELEVANCE: Allergic diseases such as food allergy, anaphylaxis, rhinitis and asthma affect millions of Americans with billions of dollars in health care cost. In recent years, allergy prevalence and severity have been increasing dramatically world-wide. Mast cells release inflammatory mediators that cause the symptoms of asthma and other allergic diseases. This proposal is based on the identification of a novel signaling molecule that regulates mast cell function. We believe that proposed studies will generate significant new information on the regulation of mast cell function and may offer novel therapeutic approaches for the treatment of asthma and other allergic diseases.