BETA2-ADRENERGIC RECEPTOR DOWN-REGULATION IN ASTHMA

Stacie Jones博士是一名助理教授，她于1994年完成了儿科过敏/免疫学研究。在这个提案中，她概述了一个研究长期β受体激动剂治疗对哮喘患者β 2肾上腺素能受体（beta2AR）调节的影响的计划。发展对-受体激动剂的耐受性一直是哮喘相关性支气管痉挛治疗的一个重要问题。体外和体内研究都表明β - 2ar密度的变化与β -激动剂长期暴露有关。将β 2ar运输到溶酶体进行降解描述了下调的过程。尽管它在决定对β激动剂的反应性方面很重要，但人们对beta2AR下调的分子机制知之甚少。本项目提出采用一种新的方法，利用β - 2ar -表皮生长因子受体嵌合体来确定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负责溶酶体分选和β - 2ar在长期β激动剂暴露后的下调。在实验室中获得的信息将应用于床边的转化研究，以将哮喘患者beta2AR基因多态性与beta2AR下调的细胞机制联系起来。该研究的核心假设是，beta2AR下调是由可溶性细胞内蛋白与beta2AR溶酶体靶向结构域之间的特异性相互作用驱动的，并且下调的速率受到beta2AR氨基末端区域多态性的修饰。采用一系列分子和细胞生物学技术，该假设将通过以下具体目标进行测试：1)确定驱动beta2AR转运的功能性beta2AR溶酶体靶向结构域，并确定beta2AR氨基端多态性对beta2AR下调的影响；2)确定负责beta2AR向溶酶体分选的细胞内溶酶体靶向蛋白；3)评估长期兴奋剂暴露环境下哮喘患者beta2AR受体转运和下调多态性的临床相关性。从拟议的研究中获得的信息将推进我们对β受体激动剂暴露与β 2ar下调之间关系的认识，并可能为哮喘治疗带来新的方法。PI将利用阿肯色大学强大的指导、受保护的研究时间和优秀的学术资源，实现她成为一名独立研究者的目标。

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.