Role of beta-arrestin-dependent chemotaxis in protease-activated-receptor-2-induc

描述(申请人提供)：蛋白酶激活受体-2(PAR-2)是一种G蛋白偶联受体(GPCR)，由许多类胰蛋白酶激活，其中许多发现于炎症部位或可能由入侵的病原体释放(5；7)。目前的研究表明，PAR-2在哮喘和结肠炎等炎症性疾病中可能具有保护和致病作用，这取决于疾病模型、PAR-2激动剂的应用和生理读数(1-4；8；11；14-16)。我们的实验室已经证明了PAR-2的多种G蛋白非依赖性作用，这些作用是由一个被称为2-arrestins(6；9；10；13；17；18)的蛋白家族介导的。2-arrestins有效地从G-蛋白途径“窃取”信号分子，其中一些直接抑制另一些只在特定细胞微区激活的信号分子。此外，2-arrestins可以招募和激活不受G-蛋白偶联影响的分子(17；18)。这种依赖于2-arrestin的PAR2信号机制允许一个受体以特定细胞类型的方式协调不同的生理事件。最近，PAR-2作为哮喘和其他炎症性疾病的治疗靶点引起了大量的兴趣(4；12)；然而，一些小组建议使用激动剂，另一些小组建议使用PAR2的拮抗剂作为治疗药物。这项资助通过评估缺乏2-arresstins的小鼠(基因敲除小鼠)中PAR2诱发的哮喘，以及通过将PAR-2基因敲除小鼠的骨髓移植到野生型中，检验了新的假设，即2-arrestin依赖和G-蛋白依赖的信号可能在不同类型的细胞中主导，从而导致一些炎症和一些保护性反应。阐明每条信号通路在炎症中的特定作用可能导致发展通路特异性的PAR2激动剂和/或拮抗剂。 公共卫生相关性：目前，蛋白酶激活受体-2(PAR2)被认为是治疗哮喘、结肠炎和癌症的靶点；然而，对于其在炎症中的实际作用仍存在相当大的争议。一些组织建议将雾化激活剂作为哮喘的治疗方法，而另一些组织则建议拮抗它以达到抑制炎症的目的。这项建议旨在剖析PAR-2在呼吸道中的促炎和抗炎作用的途径，希望这可能导致最终开发途径特异性药物。

DESCRIPTION (provided by applicant): Protease-activated-receptor-2 (PAR-2) is a G-protein-coupled-receptor (GPCR) activated by a number of trypsin-like proteases, many of which are found at sites of inflammation or may be released by invading pathogens(5; 7). Current studies indicate that PAR-2 may have both protective and pathogenic effects in inflammatory diseases such as asthma and colitis, depending on the disease model, the administration of PAR-2 agonist and the physiological read-out (1-4; 8; 11; 14-16). Our laboratory has demonstrated multiple G-protein-independent effects of PAR-2, that are mediated by a family of proteins called 2-arrestins (6; 9; 10; 13; 17; 18). 2-arrestins effectively 'steal' signaling molecules from the G-protein pathway, some of which they directly inhibit others of which are activated only in specific cellular microdomains. Additionally, 2-arrestins can recruit and activate molecules not affected by G-protein coupling (17; 18). This 2-arrestin-dependent PAR2 signaling mechanism allows one receptor to orchestrate different physiological events in a cell-type specific manner. Recently, there has been a substantial amount of interest in PAR-2 as a therapeutic target for asthma and other inflammatory disorders (4; 12); however, while some groups propose agonists others propose antagonists of PAR2 as therapeutics. This grant tests the novel hypothesis that 2-arrestin-dependent and G-protein-dependent signals may dominate in different cell types leading to some inflammatory and some protective responses, by assessing PAR2 evoked asthma in mice lacking either of the two 2-arrestins (knockout mice), and by transplanting bone marrow of PAR-2 knockout mice into wild type. Elucidation of the specific role of each signaling pathway in inflammation could lead to the development of pathway specific PAR2 agonists and/or antagonists. Public Health Relevance: Currently Protease-activated-receptor-2 (PAR2) is being considered as a target for treatment of asthma, colitis and cancer; however, there exists considerable controversy over its actual role in inflammation. Some groups are proposing aerosolized activators as a treatment for asthma, while others propose antagonizing it to achieve suppression of inflammation. This proposal aims to dissect the pathways leading to pro and anti-inflammatory effects of PAR-2 in the airways, with the hope that this may lead to the eventual development of pathway-specific drugs.