BETA2-ADRENERGIC RECEPTOR DOWN-REGULATION IN ASTHMA

Stacie Jones博士是一名助理教授，于1994年完成了她的儿科过敏/免疫学研究员职位。在这项提案中，她概述了一个项目，以研究长期的β-激动剂治疗对哮喘患者β2肾上腺素能受体(β2AR)调节的影响。在哮喘相关的支气管痉挛的治疗中，对β-激动剂的耐受性的发展一直是一个重要的问题。体外和体内研究都表明，随着β-受体激动剂暴露时间的延长，β-2AR密度发生了变化。将β-2AR转运到溶酶体进行降解描述了下调调控的过程。尽管它在确定对β-激动剂的反应性方面很重要，但人们对驱动β-2AR下调的分子机制知之甚少。该项目建议使用一种新的方法，利用β-2AR-apikin生长因子受体嵌合体来定义重要的分子决定因素和细胞内蛋白相互作用，这些分子决定因素和细胞内蛋白相互作用是导致溶酶体分选和长期暴露于β-激动剂后β2AR下调的原因。实验室中获得的信息将被应用于床边的翻译研究，以将哮喘患者β2AR下调的细胞机制与β2AR的遗传多态联系起来。这一建议的中心假设是，β2AR下调是由可溶性细胞内蛋白与β2AR溶酶体靶向结构域之间的特定相互作用驱动的，下调的速度受到β2AR氨基末端区域的多态性的影响。利用一系列分子和细胞生物学技术，这一假说将通过以下具体目标进行验证：1)确定驱动β2AR转运的功能β2AR溶酶体靶向结构域，并确定β2AR氨基末端多态对β2AR下调的影响；2)确定负责将β2AR分类到溶酶体的细胞内溶酶体靶向蛋白(S)；以及3)评估在长时间激动剂暴露的情况下，β2AR基因多态性在哮喘患者受体转运和下调中的临床相关性。从拟议的研究中获得的信息将促进我们对β-激动剂暴露和β-2AR下调之间的联系的了解，并可能导致哮喘治疗的新方法。PI将利用阿肯色大学强大的导师、受保护的研究时间和出色的学术资源来实现她成为一名独立调查员的目标。

Dr. Stacie Jones, the PI, is an assistant professor who completed her pediatric allergy/immunology fellowship in 1994. In this proposal, she outlines a program to study the effects of prolonged beta-agonist treatment on beta2 adrenergic receptor (beta2AR) regulation in patients with asthma. Development of tolerance to beta-agonists has been a significant concern in the treatment of asthma-related bronchospasm. Both in vitro and in vivo studies have demonstrated change in beta2AR density in relation to prolonged beta-agonist exposure. Trafficking of beta2AR to lysosomes for degradation describes the process of down-regulation. Despite its importance in determining responsiveness to beta-agonists, little is known about the molecular mechanisms driving beta2AR down-regulation. This project proposes to use a novel approach employing beta2AR- apidermal growth factor receptor chimeras to define the important molecular determinants and intracellular protein interactions that are responsible for lysosomal sorting and beta2AR down- regulation following prolonged beta-agonist exposure. Information gained in the laboratory will be applied in translational research at the bedside to correlate-the cellular mechanisms responsible for beta2AR down-regulation with genetic polymorphisms of the beta2AR in asthmatics. The central hypothesis of this proposal is that beta2AR down-regulation is driven by specific interaction between a soluble intracellular protein with a beta2AR lysosomal targeting domain and that the rate of down-regulation is modified by polymorphisms in the amino-terminal region of the beta2AR. Employing a series of molecular and cellular biology techniques, the hypothesis will be tested via the following Specific Aims: 1) Identify the functional beta2AR lysosomal targeting domain driving beta2AR trafficking and define the impact of beta2AR amino-terminus polymorphisms on beta2AR down-regulation, 2) Determine the intracellular lysosomal targeting protein(s) responsible for beta2AR sorting to lysosomes, and 3) Assess the clinical relevance of beta2AR polymorphisms in receptor trafficking and down-regulation in asthmatics in the setting of prolonged agonist exposure. Information gained from the proposed studies will advance our knowledge of the association between beta-agonist exposure and beta2AR down-regulation and may led to new approaches in asthma therapeutics. The PI will take advantage of the strong mentoring, protected research time and the outstanding academic resources of the University of Arkansas for Medical Sciences to reach her goal of becoming an independent investigator.