NHERF1 regulates MRGPRX2/MrgprB2 responses in mast cells

项目摘要 肥大细胞是组织驻留的先天性免疫细胞，其最佳特征在于其在介导免疫应答中的作用。 过敏性疾病肥大细胞研究的一个新进展是鉴定和表征肥大细胞， 新的G蛋白偶联受体，Mass相关G蛋白偶联受体X2（MRGPRX 2）。该受体 促进对美国食品和药物管理局（FDA）批准的药物和慢性 炎症的疾病，如哮喘，红斑痤疮和荨麻疹（荨麻疹）。虽然MRGPRX 2在促进 过敏反应已被彻底研究，该受体利用的分子机制很差， 明白我们的数据表明，Na+/H+交换调节因子（NHERF）1，一种衔接蛋白，调节 MRGPRX 2-和MrgprB 2-（人受体的小鼠直系同源物）诱导肥大细胞的反应。 具体地说，肥大细胞中NHERF 1表达的减少导致细胞内Ca 2+动员的减少 并通过MRGPRX 2/MrgprB 2体外脱颗粒。与此数据一致，NHERF 1也促进了 在MrgprB 2依赖性小鼠爪水肿和体内被动全身过敏反应模型中的过敏反应。这 一项提案建立在这些观察的基础上;中心假设是NHERF 1是一个关键的调节因子， 肥大细胞中的MRGPRX 2应答。使用我们最近产生的一种新的小鼠品系，Cpa 3- Cre+：NHERF 1fl/fl、原代人CD 34+干细胞衍生的肥大细胞和人源化小鼠，我们将确定Cre+：NHERF 1fl/fl、原代人CD 34+干细胞衍生的肥大细胞的表达。 肥大细胞特异性表达NHERF 1在调节小鼠MrgprB 2和人MRGPRX 2受体中的作用 在体外和体内（目标1）。在目标2中，我们将探讨NHERF 1调节肥大细胞的机制。 细胞反应。具体地说，我们将确定NHERF 1的磷酸化是否对NHERF 1 MRGPRX 2/MrgprB 2的调节。我们将确定NHERF 1相互作用组和信号传导的组成部分， 通过使用转录组学和蛋白质组学方法研究NHERF 1在肥大细胞中发挥功能的蛋白质和途径 接近。此外，我们将描述NHERF 1-microRNA（miR）155-细胞因子抑制因子的作用， 信号转导（SOCS 1）-Src同源2（SH 2）结构域含肌醇多磷酸5-磷酸酶1（SHIP-1） 轴促进肥大细胞活化。鉴于肥大细胞-MRGPRX 2在引起假性过敏中的关键作用， 过敏性疾病的反应和慢性炎症，阐明NHERF 1 导致MRGPRX 2介导的过敏反应具有重要的科学和临床意义。我们坚决 我相信，成功地完成拟议的研究将可能导致确定潜在的目标 MRGPRX 2通路的研究，不仅可以为药物的未来发展提供见解， 假性过敏反应，以及其他肥大细胞介导的炎性疾病。

PROJECT SUMMARY Mast cells are tissue resident innate immune cells that have been best characterized for their role in mediating allergic diseases. A new development in mast cell research has been the identification and characterization of a novel G-protein coupled receptor, Mas-Related G-Protein-coupled Receptor X2 (MRGPRX2). This receptor promotes pseudoallergic reaction to U.S. Food and Drug Administration (FDA)-approved drugs and chronic inflammation in diseases such as asthma, rosacea and hives (urticaria). While the role of MRGPRX2 in promoting allergic reactions has been thoroughly investigated, the molecular mechanisms utilized by this receptor is poorly understood. Our data suggests that Na+/H+ exchanger regulatory factor (NHERF)1, an adaptor protein, regulates MRGPRX2- and MrgprB2- (the mouse ortholog of the human receptor) induced responses in mast cells. Specifically, reducing the expression of NHERF1 in mast cells results in decreased intracellular Ca2+ mobilization and degranulation via MRGPRX2/MrgprB2 in vitro. Consistent with this data, NHERF1 also promoted anaphylaxis in MrgprB2-dependent mouse models of paw edema and passive systemic anaphylaxis in vivo. This proposal builds up on these observations; the central hypothesis is that NHERF1 is a critical regulator of MRGPRX2 responses in mast cells. Using a novel mouse strain that we have recently generated, Cpa3- Cre+:NHERF1fl/fl, primary human CD34+ stem cell-derived mast cells and humanized mice, we will determine the role of mast cell-specific expression of NHERF1 in regulating mouse MrgprB2 and human MRGPRX2 receptors in vitro and in vivo (Aim 1). In Aim 2, we will explore the mechanisms through which NHERF1 modulates mast cell response. Specifically, we will determine whether phosphorylation of NHERF1 is important for NHERF1 regulation of MRGPRX2/MrgprB2. We will identify the components of the NHERF1-interactome and signaling proteins and pathways through which NHERF1 functions in mast cells by using transcriptomic and proteomic approaches. Additionally, we will delineate the role of NHERF1-microRNA (miR)155-suppressor of cytokine signaling (SOCS1)-Src homology 2 (SH2) domain containing inositol polyphosphate 5-phosphatase 1 (SHIP-1) axis in promoting mast cell activation. Given the critical role of mast cell-MRGPRX2 in causing pseudoallergic reactions and chronic inflammation in allergic diseases, elucidation of the mechanisms by which NHERF1 contributes to MRGPRX2-mediated allergic response is of significant scientific and clinical importance. We firmly believe that successful completion of the proposed studies will likely lead to the identification of potential targets of the MRGPRX2 pathway that can provide insights into the future development of drugs for not only pseudoallergic reactions but also other mast cell-mediated inflammatory diseases.