Novel Molecular Mechanisms Promote GPCR-Induced Bronchodilation in Asthma

描述（由申请人提供）：从主题上讲，我们的跨学科PPG提案已经进行了重大修改，探索了抑制人类气道平滑肌（HASM）收缩和促进支气管扩张的新分子机制。主要假设认为，G蛋白偶联受体（GPCR）脱敏和无偏倚信号限制了传统支气管扩张剂的疗效。针对这些机制将为哮喘提供更好的治疗方法。在项目1中，类固醇阻止慢性b2 -肾上腺素能受体（B2AR）对3-激动剂快速反应的机制将表征GPCR激酶（GRK）介导的B2AR脱敏和再敏。项目2将推进最近发现的苦味受体（TAS2Rs）作为新型支气管扩张剂，阐明TAS2R亚型在ASM中的作用，其调节模式以及通过偏倚激动作用提高其疗效的方法。在项目3中，系统地描述ASM中B2AR和gq偶联受体调节模式的方法将被定义为靶向GRK和抑制素对B2AR脱敏和偏B2AR激活的调节，使用gq偶联受体信号的变抗调节剂或抑制剂来保护促收缩介质。在项目4中，将定义假设的质子传感OGR1在调节ASM功能中的功能和调控，并发现配体和调控策略，使OGR1的多效信号倾向于促松弛途径。这四个项目将由核心A支持，将使用高通量筛选小分子文库、全基因组、汇集shRNA文库和虚拟筛选方法来识别支气管扩张的靶点和效应物。Core B将提供所有未鉴定的人类细胞和组织模型，以研究HASM中E-C偶联的新机制。核心C将为该计划提供行政支持。该PPG将提供：改进对HASM中GPCR脱敏的理解，识别促进gq依赖性支气管扩张的独特分子，定义新的TAS2Rs激动剂和OGR1拮抗剂以防止支气管收缩。

DESCRIPTION (Provided by applicant): Thematically, our interdisciplinary PPG proposal, which has undergone significant revision, explores novel molecular mechanisms to inhibit human airway smooth muscle (HASM) contraction and promote bronchodilation. The principal hypothesis states that G protein-coupled receptor (GPCR) desensitization and unbiased signaling limit efficacy of conventional bronchodilators. Targeting these mechanisms will provide improved therapy for asthma. In Project 1, the mechanism by which steroids deter chronic B2-adrenergic receptor (B2AR) tachyphylaxis to 3-agonists will characterize GPCR kinase (GRK)-mediated desensitization and resensitization of the B2AR. Project 2 will advance the recent discovery of bitter taste receptors (TAS2Rs) as novel bronchodilators clarifying the role of TAS2R subtypes in ASM, their mode of regulation and means to improve their efficacy through biased agonism. In Project 3, systematic approaches to characterize the modes of B2AR and Gq-coupled receptor regulation in ASM will be defined to target GRK and arrestin regulation of B2AR desensitization and biased B2AR activation using allosteric modulators or inhibitors of Gq-coupled receptor signaling to protect against pro-contractile mediators. In Project 4, the function and regulation ofthe putative proton-sensing OGR1 in modulating ASM function will be defined, and ligands and regulatory strategies discovered to bias pleiotropic signaling of OGR1 toward pro-relaxant pathways. The four projects will be supported by Core A that will use high through-put screening of small molecule libraries, whole genome, pooled shRNA libraries and virtual screening approaches to identify targets and effectors of bronchodilation. Core B will provide all de-identified human cell and tissue models to study novel mechanisms regulating E-C coupling in HASM. Core C will provide administrative support for the program. This PPG will deliver: an improved understanding of GPCR desensitization in HASM, identify unique molecules that promote Gq-dependent bronchodilation, define novel agonists to TAS2Rs and antagonists to OGR1 to prevent bronchoconstriction.