MAST CELL ADENOSINE RECEPTOR

腺苷在急性心肌梗死发病机制中的重要性 超敏反应越来越明显。 腺苷， 从缺氧的肺组织或激活的肥大细胞释放， 颗粒相关肥大细胞介质的刺激释放， 体外 在体哮喘患者吸入腺苷诱发支气管痉挛 受试者通过一种机制， 预先形成的肥大细胞介质的低水平释放，特别是 组胺 肥大细胞至少具有两种细胞表面 腺苷受体，单独或组合导致 磷脂酶C和腺苷酸环化酶的活化。 受体占据 单独不足以诱导介质释放， 腺苷不能增强白细胞三烯和白细胞三烯的活性。 性质 这些肥大细胞腺苷受体，它们各自的信号 转导途径，对调节刺激的反应，以及 每种亚型在肥大细胞分泌中重要性在很大程度上是未知的。 该项目的范围包括一个彻底的生理和 两个新克隆的肥大细胞腺苷的药理学特性 受体亚型 受体将在稳定表达中进行研究 系统如转染CHO细胞以及反义敲除 在转染的RBL细胞中的实验。 抗细胞内和 将产生每种受体的胞外结构域， 定量受体表达并检查肥大细胞功能的变化 在特定抗体的存在下。 腺苷受体的调节 将在mRNA和蛋白质水平上利用几个 先前显示可改变肥大细胞中腺苷受体表达的药物 细胞 在选定的磷酸化位点的定点诱变可以 帮助确定在脱敏和降低中重要的激酶， 监管回应。 因为腺苷是一种天然存在的 过敏反应的介质和调节剂，更清楚地了解 肥大细胞腺苷受体将促进 用于治疗哮喘和过敏性疾病的治疗性干预 疾病

The importance of adenosine in the pathogenesis of immediate hypersensitivity reactions is becoming increasingly clear. Adenosine, released from hypoxic lung tissue or activated mast cells, potentiates the stimulated release of granule-associated mast cell mediators in vitro. In vivo, inhaled adenosine induces bronchospasm in asthmatic subjects by a mechanism consistent with the augmentation of an ongoing, low-level release of preformed mast cell mediators, particularly histamine. Mast cell possess at least two types of cell surface adenosine receptors that singly or in combination result in the activation of phospholipase C and adenylate cyclase. Receptor occupation alone is not sufficient to induce mediator release, and the release of leukotrienes and prostaglandins is not enhanced by adenosine. The nature of these mast cell adenosine receptors, their individual signal transduction pathways, responses to regulatory stimuli, and the importance of each subtype in mast cell secretion are largely unknown. The scope of the project encompasses a thorough physiologic and pharmacologic characterization of two newly-cloned mast cell adenosine receptor subtypes. Receptors will be studied in a stable expression system such as transfected CHO cells as well as in anti-sense knock out experiments in transfected RBL cells. Antibodies to intracellular and extracellular domains of each receptor will be produced in order to quantitate receptor expression and examine changes in mast cell function in the presence of specific antibody. Regulation of adenosine receptor numbers will be studied at the mRNA and protein levels utilizing several agents previously shown to alter adenosine receptor expression in mast cells. Site-directed mutagenesis at selected phosphorylation sites may help to determine the kinases important in desensitization and down- regulation responses. Because adenosine is a naturally-occurring mediator and modulator of allergic responses, a clearer understanding of mast cell adenosine receptors will facilitate the development of therapeutic interventions useful in the treatment of asthma and allergic diseases.