Regulation of Normal and Asthmatic Lung Function by G-Protein-Coupled Receptors

G 蛋白偶联受体对正常和哮喘肺功能的调节

• 批准号: 8946374
• 负责人: Kirk m Druey
• 金额: $ 43万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8946374
• 关键词: Actins; Acute; Adenosine; Adrenergic beta-Agonists; Agonist; Albuterol; Allergens; Allergic inflammation; Animal Model; Asthma; Binding; Bradykinin; Bronchoalveolar Lavage Fluid; Bronchodilator Agents; Calcium; Cell Count; Cell Culture Techniques; Cells; Chronic; Collaborations; Collagen; Contracts; Cyclic AMP; Cytoplasmic Granules; Deposition; Development; Disease susceptibility; Drug Targeting; Endothelin-1; Extrinsic asthma; Family; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; G-substrate; GTP-Binding Protein Regulators; GTP-Binding Protein alpha Subunits; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Proteins; Gene Deletion; Generations; Goals; Guanosine Triphosphate Phosphohydrolases; Heterotrimeric GTP-Binding Proteins; Histamine; Homeostasis; Human; Hyperplasia; IgE; Interleukin-13; Leukotriene Antagonists; Leukotriene D4; Ligands; Lung; Lung Inflammation; Mediating; Michigan; Mitogens; Modeling; Mucins; Mus; Muscle Contraction; Muscle Fibers; Muscle function; Muscle relaxation phase; Myosin ATPase; Obstruction; Peptide Hydrolases; Phenotype; Physiological; Production; Protein Binding; RGS Domain; RGS Proteins; Regulation; Relative (related person); Relaxation; Respiratory physiology; Role; Signal Pathway; Slice; Smooth Muscle; Smooth Muscle Myocytes; Specimen; Steroids; Thrombin; Tissues; Universities; airway obstruction; allergic airway inflammation; cysteinyl-leukotriene; eosinophilic inflammation; inhibitor/antagonist; interest; mast cell; muscle form; overexpression; receptor coupling; repository; respiratory smooth muscle

Asthma, a pathological condition of reversible airway obstruction, is comprised of both inflammation of the lung and hyper-contractility of the bronchiolar smooth muscle. The major naturally occurring substances that induce bronchial smooth muscle contraction are ligands of G-protein-coupled receptors (GPCRs), such as allergen proteases, thrombin, and those contained in allergen-IgE activated mast cell granules (e.g. histamine, cysteinyl leukotrienes (LTD4), endothelin 1, adenosine, and bradykinin). In general, these agonists induce activation of the heterotrimeric G protein G-alpha q, which increases the concentration of intracellular calcium in smooth muscle cells, promoting actin-myosin interactions and muscle fiber shortening. In contrast, ligands acting on G-alpha-s-coupled receptors, such as albuterol, increase intracellular levels of cyclic AMP (cAMP), facilitating ASM relaxation. Although eosinophilic inflammation typifies allergic asthma, it is not a prerequisite for AHR, suggesting that underlying abnormalities in structural cells such as airway smooth muscle (ASM) contribute to the asthmatic diathesis. Dysregulation of procontractile, GPCR signaling in ASM could mediate enhanced contractility. A large family of Regulators of G protein signaling (RGS) proteins binds to the G protein alpha subunits Gi and Gq (but not Gs) through a conserved RGS domain and inactivates them by catalyzing their intrinsic GTPase activity and by blocking downstream effector interactions. Although they are generally considered to act as negative regulators of GPCR signaling pathways, the physiological function of RGS proteins in the lung is mostly unknown. We identified expression of several RGS proteins (particularly RGS4, RGS5) in bronchial smooth muscle. In FY14, we demonstrated that the mice genetically deficient in RGS5 developed spontaneous asthma due to abnormal GPCR-induced Ca2+ homeostasis in ASM. Precision-cut lung slices (PCLS) from nave Rgs5-/- mice contracted maximally at baseline, independent of allergen challenge. RGS5 deficiency had little effect on parameters of allergic inflammation including cell counts in bronchoalveolar lavage fluid (BALF), mucin production, ASM mass, and subepithelial collagen deposition. Unexpectedly, IL-13 levels were much lower in BALF from Rgs5-/- mice relative to WT. These studies showed that deficiency of RGS5 confers spontaneous AHR in mice in the absence of allergic inflammation. In severe asthma, bronchodilator- and steroid-insensitive airflow obstruction develops through unknown mechanisms characterized by increased lung ASM mass and stiffness. RGS4 expression was restricted to a subpopulation of ASM and was specifically upregulated by mitogens, which induced a hyperproliferative and hypocontractile ASM phenotype similar to that observed in recalcitrant asthma. We are currently examining the phenotype of with global and smooth muscle-specifi Rgs4 gene deletion, as well as mice that overexpress RGS4,in models of acute and chronic allergic airway inflammation. In collaboration with Dr. Neubig at the University of Michigan, we will examine the effect of an RGS4-specific inhibitor on the development of the asthma phenotype and ASM hyperplasia and contraction in animal models and cell culture. This is a first-generation RGS inhibitory compound.

哮喘是一种可逆性气道阻塞的病理状态，由肺部炎症和细支气管平滑肌过度收缩组成。诱导支气管平滑肌收缩的主要天然物质是g蛋白偶联受体（gpcr）的配体，如过敏原蛋白酶、凝血酶和过敏原ige激活的肥大细胞颗粒中含有的配体（如组胺、半胱氨酸白三烯（LTD4）、内皮素1、腺苷和缓激肽）。一般来说，这些激动剂诱导异三聚体G蛋白G- α q的激活，从而增加平滑肌细胞内钙的浓度，促进肌动蛋白-肌球蛋白相互作用和肌纤维缩短。相反，作用于g - α -s偶联受体的配体，如沙丁胺醇，增加细胞内环AMP （cAMP）水平，促进ASM松弛。虽然嗜酸性粒细胞炎症是过敏性哮喘的典型特征，但它并不是AHR的先决条件，这表明气道平滑肌（ASM）等结构细胞的潜在异常有助于哮喘的特质。ASM中促收缩性、GPCR信号的失调可能介导收缩性增强。