Roles of novel MRGPRX2/MrgprB2 signaling in mast cells on host defense and Inflammation

肥大细胞中新型 MRGPRX2/MrgprB2 信号传导在宿主防御和炎症中的作用

• 批准号: 10062477
• 负责人: Hydar Ali
• 金额: $ 40.55万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10062477
• 关键词: Adaptor Signaling Protein; Affinity; Agent 48-80; Agonist; Allergic; Arrestins; Bacterial Infections; Binding Proteins; Biological; CRISPR/Cas technology; Cell Degranulation; Cell Line; Cell Surface Receptors; Cell physiology; Cell surface; Chronic; Clinical; Connective Tissue; Coupling; Data; Disease; FDA approved; G-Protein-Coupled Receptors; GTP-Binding Proteins; Generations; Host Defense; Human; Hypersensitivity; IgE Receptors; In Vitro; Inflammation; Inflammatory; Knock-in; Knock-in Mouse; Ligand Binding; Ligands; Mediating; Mediator of activation protein; Modification; Molecular; Mus; Mutation; Natural Immunity; Neuropeptide Receptor; Neuropeptides; Neutrophil Infiltration; Opioid; Opioid Receptor; Pathogenesis; Pathway interactions; Peptides; Pharmaceutical Preparations; Phenotype; Play; Procedures; Pruritus; Reaction; Regulation; Role; Rosacea; Signal Pathway; Signal Transduction; Structure; Substance P; Urticaria; Variant; Wild Type Mouse; adaptive immunity; antimicrobial peptide; antimicrobial peptide LL-37; base; beta-arrestin; chemokine; chronic inflammatory skin; cytokine; desensitization; exome sequencing; gain of function; in vivo; loss of function; mast cell; molecular modeling; molecular sequence database; mutant; novel; novel strategies; pituitary adenylate cyclase activating polypeptide; receptor; receptor coupling; receptor expression; receptor function; recruit; response; side effect; skin disorder; transcription factor

Summary: In addition to the high affinity IgE receptor (FcεRI), human connective tissue mast cells (MCTC) express a recently described G protein coupled receptor (GPCR), known as Mas-related GPCR-X2 (MRGPRX2). Our lab was the first to demonstrate that host defense antimicrobial peptides (HDPs) activate human mast cells via MRGPRX2, which likely contributes to innate immunity. Emerging evidence suggests that MRGPRX2- mediated local mast cell activation clears bacterial infection via the recruitment of neutrophils and promotes adaptive immunity to control reinfection. However, dysregulation of host defense and excessive generation of the host defense peptide, LL-37 contributes to the pathogenesis of rosacea. MrgprB2 is the mouse counterpart of human MRGPRX2 and our preliminary data demonstrated that LL-37-mediated experimental rosacea is significantly reduced in MrgprB2-/- mice when compared to wild-type mice. MRGPRX2 also serves as a novel GPCR for neuropeptides such as substance P, hemokinin-1 and pituitary adenylate cyclase- activating peptide (PACAP). Furthermore, MRGPRX2 is an “atypical opioid receptor” and some of the side effects opioids are likely mediated via mast cell degranulation through this receptor. However, the molecular mechanisms involved in the activation and regulation of its downstream signaling remains largely unknown. In addition to G proteins, many GPCR agonists also signal via the recruitment of adapter proteins known as β-arrestins. This pathway not only contributes to GPCR desensitization but also provides a platform for a variety of G protein-independent signaling. Biased GPCR agonists preferentially activate pathways mediated by G proteins (G protein-biased) or β-arrestins (β-arrestin-biased). Agonists that activate both pathways are known as balanced agonists. Recently, we made the surprising observation that while compound 48/80 activates both G protein and β-arrestin (balanced agonist) an angiogenic host defense peptide activates only G protein but not β-arrestin (G protein-biased agonist). Based on these findings, we hypothesize that balanced and G protein-biased MRGPRX2 agonists activate mast cells via different mechanisms to promote distinct biological responses in vivo. Because MrgprB2 is the mouse counterpart of the human MRGPRX2, we will incorporate this receptor for many of our in vivo studies. In aim #1, we will determine which of the known mast cell secretagogues (HDPs, neuropeptides, opioids and FDA-approved pseudo-allergic drugs) act as balanced and G protein-biased agonists for MRGPRX2. We will also identify the structural determinants on the receptor that facilitate their coupling to G protein and β-arrestins. In aim #2, we will modulate host defense, pseudo-allergy and rosacea by targeting MRGPRX2/MrgprB2’s balanced/G protein biased signaling in mast cells in vivo. In aim #3, we will determine the roles of β-arrestin1 and β-arrestin2 on MRGPRX2 and MrgprB2-mediated signaling in vitro and biological responses in vivo. Completion of this study will provide novel approaches to modulate MRGPRX2-mediated host defense and inflammatory diseases.

摘要： 除了高亲和力的Ig E受体(FcεRI)外，人结缔组织肥大细胞(MCTC)还表达 最近发现了一种G蛋白偶联受体(GPCR2)，称为Mas相关GPCRX2(MRGPRX2)。我们的 实验室首先证明了宿主防御抗菌肽(HDPs)能激活人类肥大细胞 通过MRGPRX2，这可能有助于天然免疫。新出现的证据表明，MRGPRX2- 介导的局部肥大细胞激活通过中性粒细胞的募集清除细菌感染并促进 控制再感染的适应性免疫。然而，寄主防御失调和过度繁殖 在宿主防御肽中，LL-37与酒渣鼻的发病机制有关。他就是那只老鼠 人MRGPRX2的对应物和我们的初步数据表明，LL-37介导的实验 与野生型小鼠相比，mrgprB2-/-小鼠的酒渣鼻症状显著减少。MRGPRX2还提供 作为一种新的P物质、血红素-1和垂体腺苷环化酶等神经肽的GPCR- 活化肽(PACAP)。此外，MRGPRX2是一种“非典型阿片受体”，其部分副作用 阿片类药物的作用可能是通过该受体介导的肥大细胞脱颗粒。然而，分子 其下游信号的激活和调控机制目前仍不清楚。 除了G蛋白外，许多GPCR激动剂还通过募集适配蛋白来传递信号 被称为β-Drastins。这条途径不仅有助于GPCR脱敏，而且还提供了一个平台 对于各种G蛋白不依赖的信号传导。偏向GPCR型激动剂优先激活通路 由G蛋白(偏重G蛋白)或β-拦阻蛋白(偏重β-arrestin)介导。两种激动剂都能激活 通路被称为平衡激动剂。最近，我们做了一个令人惊讶的观察，虽然化合物 48/80同时激活G蛋白和β-arrestin(平衡激动剂)-血管生成宿主防御肽激活 只有G蛋白，而不是β-arrestin(G蛋白偏向激动剂)。基于这些发现，我们假设 平衡的和G蛋白偏向的MRGPRX2激动剂通过不同的机制激活肥大细胞 促进体内不同的生物反应。因为Mr gprB2是人类的老鼠 MRGPRX2，我们将在许多体内研究中加入这种受体。在目标1中，我们将确定哪一个 已知的肥大细胞促分泌剂(HDPs、神经肽、阿片类药物和FDA批准的假性过敏 药物)作为MRGPRX2的平衡和偏重于G蛋白的激动剂。我们还将确定结构 受体上的决定因素，促进其与G蛋白和β-拦阻蛋白的偶联。在目标2中，我们将 靶向MRGPRX2/MRGPrB2‘S平衡/G蛋白调控宿主防御、假变态反应和酒渣鼻 体内肥大细胞中的偏向信号。在目标3中，我们将确定β-arrestin1和β-arrestin2在 MRGPRX2和MRGPrB2介导的体外信号转导和体内生物反应。完成这项研究 将提供新的方法来调节MRGPRX2介导的宿主防御和炎症性疾病。