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Signaling and Crosstalk by Airway Prostanoid Receptors

气道前列腺素受体的信号传导和串扰

基本信息

批准号：
7109297
负责人：
Dennis W McGraw
金额：
$ 33.73万
依托单位：
UNIVERSITY OF CINCINNATI
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-09-01 至 2007-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Prostanoids have been implicated in the pathogenesis of bronchoconstriction and airway hyperreactivity (AHR) because they potently contract airway smooth muscle (ASM), and their levels, are elevated in asthmatic lung. Thromboxane, PGD2 and PGF2alpha contract ASM via activation of thromboxane prostanoid (TP) receptors. Even PGE2, which is generally considered a bronchodilator, has the capacity to transduce a constrictor signal via one of the receptor subtypes (EP1) for which it is the cognate ligand. However, despite their potent effects on ASM, it has been difficult to unambiguously assign pathophysiological relevance to these receptors due to pleiotropic responses resulting from the simultaneous production of constrictor and relaxant prostanoids by the same general enzymatic pathway, receptor activation by multiple ligands, and the existence of multiple receptor isoforms with different signal transduction properties. We believe these limitations can be overcome by using transgenic and gene-targeted mice to selectively modulate signal transduction by specific prostanoid receptors. In this proposal, we will test the overall hypothesis that bronchoconstriction and AHR occur when the activation of bronchoconstrictor prostanoid receptors is favored over those that promote bronchodilation. In Specific Aim 1, we will use mice that overexpress the TP receptor in combination with TP receptor deficient gene-targeted mice to determine whether TP receptors promote bronchoconstriction and AHR. The signaling pathways, which mediate TP receptor-dependent contraction will be dissected in vitro using primary ASM cells, isolated from the genetically engineered mice, and their physiologic significance determined in tracheal rings and intact mice. In Specific Aim 2, we will determine whether the EPt receptor is a mediator of bronchoconstriction and AHR. The transgenic models developed for these experiments will enable us to discriminate between the effects of EP1 receptor activation and those of the other EP receptor subtypes. Since it widely recognized that the primary physiologic actions of one G-protein-coupled receptor are frequently modulated by another, experiments in Specific Aim 3 will test the hypothesis that receptor cross talk by TP and EP1 receptors is a mechanism of (-adrenergic receptor dysfunction in ASM. This hypothesis is supported by preliminary data that show TP and EP1 receptor agonists attenuate isoproterenol-mediated relaxation of tracheal rings. Each of these aims will merge biochemical, pharmacologic and physiologic studies from cells, tissues, and whole animals so that in vitro signaling events can be directly correlated to in vivo physiological function. Completion of these aims may identify novel signaling events that have therapeutic relevance to asthma and other obstructive lung diseases.

描述（由申请人提供）：前列腺素类与支气管收缩和气道高反应性（AHR）的发病机制有关，因为它们可有效收缩气道平滑肌（ASM），并且其水平在哮喘肺中升高。血栓烷、PGD 2和PGF 2 α通过激活血栓烷前列腺素（TP）受体收缩ASM。即使是通常被认为是支气管扩张剂的PGE 2，也有能力通过其作为同源配体的受体亚型之一（EP 1）阻断收缩信号。然而，尽管它们对ASM的有效作用，但由于通过相同的一般酶促途径同时产生收缩剂和松弛剂前列腺素类的多效性反应、多种配体的受体活化以及具有不同信号转导特性的多种受体亚型的存在，很难明确地将病理生理学相关性分配给这些受体。我们相信这些限制可以通过使用转基因和基因靶向小鼠来选择性地调节特定前列腺素受体的信号转导来克服。在本研究中，我们将检验以下总体假设：当支气管收缩前列腺素受体的激活优于促进支气管扩张的受体时，支气管收缩和AHR发生。在特定目标1中，我们将使用过表达TP受体的小鼠与TP受体缺陷基因靶向小鼠组合，以确定TP受体是否促进支气管收缩和AHR。将使用从基因工程小鼠分离的原代ASM细胞在体外解剖介导TP受体依赖性收缩的信号传导途径，并在气管环和完整小鼠中确定其生理学意义。在具体目标2中，我们将确定EPt受体是否是支气管收缩和AHR的介体。为这些实验开发的转基因模型将使我们能够区分EP 1受体激活和其他EP受体亚型的影响。由于人们普遍认识到一种G蛋白偶联受体的主要生理作用经常受到另一种受体的调节，因此特定目标3中的实验将检验以下假设：TP和EP 1受体的受体串扰是ASM中β-肾上腺素能受体功能障碍的一种机制。初步数据显示TP和EP 1受体激动剂减弱异丙肾上腺素介导的气管环舒张，这一假设得到了支持。这些目标中的每一个都将合并来自细胞、组织和整个动物的生物化学、药理学和生理学研究，使得体外信号传导事件可以与体内生理功能直接相关。这些目标的完成可能会发现新的信号事件，具有治疗相关性哮喘和其他阻塞性肺疾病。