MAST CELL ADENOSINE RECEPTOR SIGNAL TRANSDUCTION

申请人建议研究小鼠骨髓的作用机制 衍生肥大细胞腺苷受体生物信号传导。腺苷是一种 即刻超敏反应的重要介体和调节物。 在低氧条件下，刺激肥大细胞释放腺苷作为一种介质 肺组织。吸入后可引起哮喘患者的支气管痉挛 研究对象。作为一种调节剂，腺苷促进组胺的释放 激活的肥大细胞。这种增强可以被腺苷受体阻断。 拮抗剂包括一种有效的抗哮喘药物茶碱。腺苷 作为肥大细胞功能调节器也很有意义，因为它 促进肥大细胞脱颗粒，但不能产生新的介质 如白三烯C4。生物化学过程中涉及的影响 肥大细胞上的腺苷和一般的信号转导 开始被理解了。最近的证据支持这种可能性 腺苷显著增强肥大细胞的能力， 颗粒相关的介质释放可能涉及蛋白质的激活 蛋白激酶C激活剂，如佛波酯或 合成的甘油二酯类似物对肥大细胞有不同的作用 介体释放，取决于所使用的促分泌剂，剂量 代理，以及添加代理的时间。然而，这一能力 腺苷促进预形成的介质释放被均匀地抑制 与这些制剂中的任何一种预先孵育，表明可能 腺苷需要与蛋白激酶C相互作用才能诱导其 中介人释放增强。然而，白三烯的生成并不是 在相同的实验条件下改变，再次强调了 两种类型的肥大细胞介质释放的解离可能性 蛋白激酶C在肥大细胞白三烯中的作用可能较小 制作。 这项提案中的关键问题包括腺苷本身在 其他药物对蛋白激酶C作用的存在与缺失 激活以及特定的蛋白质磷酸化、钙通量和 肌醇三磷酸的产生，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)，也将检查它们的 改变肥大细胞分泌、调节肥大细胞腺苷的能力 反应性，诱导白三烯的产生，激活或抑制蛋白质 并表达一种潜在的独特的蛋白质模式 磷酸化。重要的特定酶的抑制物或刺激物 将对二酰甘油代谢进行研究，以确定 肥大细胞分泌过程的调节。总的目标是 这个项目是为了更好地了解受体信号转导 关注一种已知对肥大有积极影响的物质--腺苷 细胞分泌过程。通过确定特定的位置和机制 腺苷对肥大细胞的作用，人们将有望开发出 能有效治疗哮喘和过敏症的药物 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.