MAST CELL ADENOSINE RECEPTOR SIGNAL TRANSDUCTION

申请人建议研究小鼠骨髓 衍生的肥大细胞腺苷受体生物信号传导。腺苷是一种 速发型超敏反应重要介质和调节剂。 作为一种介质，腺苷被缺氧环境中的肥大细胞刺激后释放 肺组织当吸入时，它可以引起哮喘患者的支气管痉挛， 科目作为一种调节剂，腺苷增强组胺从 激活的肥大细胞这种增强作用可被腺苷受体阻断 拮抗剂，包括茶碱，一种有效的抗哮喘药物。腺苷 作为肥大细胞功能调节剂也是令人感兴趣的，因为它 增加肥大细胞脱颗粒，但不产生新的介质 如白三烯C4。影响的生物化学过程 腺苷在肥大细胞和信号转导中的作用一般仅限于 开始被理解。最近的证据表明 腺苷显著增强肥大细胞的能力， 颗粒相关介质的释放可能涉及蛋白质的活化 激酶C蛋白激酶C激活剂，如佛波醇酯或 合成二酰基甘油类似物对肥大细胞显示不同的作用 介质释放，取决于所用的促分泌素， 试剂，以及添加试剂的时间。然而， 腺苷增强预先形成的介质释放被均匀地抑制， 与这些病原体一起进行预孵育，这表明 腺苷与蛋白激酶C相互作用以诱导其 介质释放增强。然而，白三烯的产生不是 在相同的实验条件下改变，再次强调了 两种类型肥大细胞介质释放的解离潜力 蛋白激酶C在肥大细胞白三烯中的作用可能较小 生产 这项提议的关键问题包括腺苷本身在 存在和不存在其他药物对蛋白激酶C影响 激活以及特定的蛋白磷酸化，钙流， 肌醇三磷酸生成，磷脂酶A2的产物， 磷脂酰胆碱代谢、溶血磷脂酰胆碱和脂肪酸 （特别是花生四烯酸和油酸），也将检查其 改变肥大细胞分泌、调节肥大细胞腺苷的能力 反应性，诱导白三烯产生，激活或抑制蛋白 激酶C，并表达一种潜在独特蛋白质模式 磷酸化重要的特定酶的抑制剂或刺激剂， 将研究甘油二酯代谢，以确定 调节肥大细胞分泌过程。的总体目标 该项目是为了更好地了解受体信号转导， 专注于一种药物，腺苷，已知对肥大细胞有积极影响， 细胞分泌过程通过确定特定的位点和机制， 腺苷对肥大细胞的作用，人们希望能够开发 将证明在治疗哮喘和过敏性疾病中有效的药剂 疾病

The applicant proposes to investigate the mechanism of mouse bone marrow derived mast cell adenosine receptor biosignaling. Adenosine is an important mediator and modulator of immediate hypersensitivity reactions. As a mediator, adenosine is released by stimulated mast cells in hypoxic lung tissue. When inhaled, it can induce bronchospasm in asthmatic subjects. As a modulator, adenosine enhances the release of histamine from activated mast cells. This enhancement can be blocked by adenosine receptor antagonists including theophylline, a potent anti-asthmatic drug. Adenosine is also of interest as a modulator of mast cell function in that it augments mast cell degranulation but not the generation of new mediators such as leukotriene C4. The biochemical processes involved in the effect of adenosine on mast cells and in signal transduction in general are only beginning to be understood. Recent evidence has supported the possibility that the ability of adenosine to markedly potentiate mast cell preformed, granule-associated mediator release may involve an activation of protein kinase C. Protein kinase C activators such as the phorbol esters or synthetic diacyl glycerol analogs exhibit varying effects on mast cell mediator release, depending on the secretagogue utilized, the dose of the agent, and the time of addition of the agent. However, the ability of adenosine to enhance preformed mediator release is uniformly suppressed by a preincubation with any of these agents, suggesting the possible requirement for adenosine to interact with protein kinase C to induce its mediator release augmentation. However, leukotriene generation is not altered under identical experimental conditions, again underscoring the potential for dissociation of the two types of mast cell mediator release and a possible lesser role for protein kinase C in mast cell leukotriene production. The key issues in this proposal include the effect of adenosine itself in the presence and absence of other pharmacologic agents on protein kinase C activation as well as specific protein phosphorylation, calcium fluxes, and inositol trisphosphate generation, the phospholipase A2 products of phosphatidylcholine metabolism, lysophosphotidylcholine and fatty acids (particularly arachidonic and oleic acids), will also be examined for their ability to alter mast cell secretion, modulate mast cell adenosine responsiveness, induce leukotriene production, activate or inhibit protein kinase C, and express a potentially unique pattern of protein phosphorylation. Inhibitors or stimulators of specific enzymes important in diacylglycerol metabolism will be studied to identify key areas of regulation of the mast cell secretory process. The overall objective of this project is to better understand receptor signal transduction by focusing on an agent, adenosine, known to positively influence the mast cell secretory process. By determining specific sites and mechanisms of action of adenosine on mast cells, one would hope to be able to develop agents that would prove efficacious in the treatment of asthma and allergic diseases.