MAST CELL ADENOSINE RECEPTOR

腺苷在即刻糖尿病发病机制中的重要作用 过敏性反应越来越明显。腺苷， 从缺氧的肺组织或激活的肥大细胞释放出来，增强 颗粒相关肥大细胞介质的刺激释放 体外培养。体内吸入腺苷诱导哮喘大鼠支气管痉挛 通过一种与正在进行的、 预先形成的肥大细胞介质的低水平释放，特别是 组胺。肥大细胞至少有两种细胞表面 单独或组合的腺苷受体导致 磷脂酶C和腺苷环化酶的激活。受体占有率 单独的不足以诱导介体释放，而释放 腺苷不会增加白三烯和前列腺素。大自然 在这些肥大细胞腺苷受体中，它们各自的信号 转导通路，对调节刺激的反应，以及 各亚型在肥大细胞分泌中的重要性在很大程度上尚不清楚。 该项目的范围包括彻底的生理和 两个新克隆的肥大细胞腺苷的药理性质 受体亚型。受体将在稳定表达的情况下进行研究 如转基因CHO细胞和反义基因敲除系统 在转基因的RBL细胞中进行实验。细胞内和细胞内抗体 每个受体的胞外区将被产生，以便 定量检测肥大细胞受体表达和功能的变化 在有特异性抗体存在的情况下。腺苷受体的调节 数字将在信使核糖核酸和蛋白质水平上进行研究，使用几个 先前显示的改变肥大细胞腺苷受体表达的药物 细胞。在选定的磷酸化位点上的定点突变可能 帮助确定在脱敏和下调过程中重要的激酶- 监管反应。因为腺苷是一种自然产生的 过敏反应的中介物和调节物，更清楚地理解 肥大细胞腺苷受体将促进 对哮喘和过敏症有效的治疗干预措施 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.