Novel Molecular Mechanisms Promote GPCR-Induced Bronchodilation in Asthma

描述（由申请人提供）：在主题上，我们的跨学科PPG提案经过了重大修订，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型分子机制。主要假设指出，G蛋白偶联受体（GPCR）脱敏和无偏信号传导限制了传统支气管扩张剂的疗效。靶向这些机制将为哮喘提供更好的治疗。在项目1中，类固醇阻止慢性B2肾上腺素能受体（B2 AR）对β-激动剂快速耐受的机制将表征GPCR激酶（GRK）介导的B2 AR脱敏和再敏化。项目2将推进苦味受体（TAS 2 R）作为新型支气管扩张剂的最新发现，阐明TAS 2 R亚型在ASM中的作用，其调节模式以及通过偏性激动提高其疗效的方法。在项目3中，将定义表征ASM中B2 AR和Gq偶联受体调节模式的系统方法，以靶向GRK和抑制蛋白调节B2 AR脱敏和偏置B2 AR激活，使用Gq偶联受体信号传导的变构调节剂或抑制剂保护免受促收缩介质的影响。在项目4中，将定义假定的质子敏感OGR 1在调节ASM功能中的功能和调节，并发现将OGR 1的多效性信号传导偏向于促松弛途径的配体和调节策略。这四个项目将得到核心A的支持，核心A将使用高通量筛选小分子文库、全基因组、合并的shRNA文库和虚拟筛选方法来鉴定支气管扩张的靶点和效应物。核心B将提供所有去识别的人类细胞和组织模型，以研究调节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：提高对HASM中GPCR脱敏的理解，鉴定促进Gq依赖性支气管扩张的独特分子，定义TAS 2 R的新型激动剂和OGR 1的拮抗剂以预防支气管收缩。

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.