Endosome sorting of human beta2-adrenoceptors

人β2-肾上腺素受体的内体分选

• 批准号: 7270521
• 负责人: Robert H Moore
• 金额: $ 32.77万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7270521
• 关键词: Endosome; sorting; human; beta2; adrenoceptors

DESCRIPTION (provided by applicant): Description: The most commonly used agents in the treatment of asthma are drugs that activate human beta2-adrenergic receptors (¿2ARs), leading to the relaxation of constricted airways. The surface expression of (¿2ARs on cells is a key determinant of their signaling capacity in response to ¿-agonists. After exposure to agonist, most ¿2ARs rapidly traffic from the cell surface into early endosomes by clathrin-dependent endocytosis. Following this, ¿2ARs may be sorted to either the recycling pathway, and thereby repopulate the cell surface with resensitized receptors, or be transported to lysosomes where they are degraded (a process termed downregulation). The mechanisms governing these sorting steps at the level of the early endosome are poorly understood, although the trafficking of ¿2ARs to lysosomes and their subsequent downregulation probably requires receptor ubiquitination and involves proteasomes. Our long-range goal is to define the molecular machinery regulating these sorting steps and how the endosome sorting of ¿2ARs modulates the surface expression and resensitization of receptors following agonist-triggered desensitization. For this application, we propose the following three specific aims: (1). determine if Mrs regulates rapid ¿2AR recycling and resensitization through its interaction with Actinin-4/BERP/Myosin Vb (thereby forming the CART complex); (2). elucidate the role of the human Vps34-interacting protein, the rab7 GPTase, in the regulation of P2AR recycling; (3). determine if the rab7-interacting protein, XAPC7, regulates P2AR trafficking by linking proteasome function and the endocytic pathway. These aims will be accomplished using a combination of complementary molecular, biochemical, and advanced microscopic techniques. The proposed studies will be performed in HEK293 cells, and key findings will be confirmed in cultured human airway cells. Relevance: We expect that these studies will provide new targets for therapeutic interventions to increase the surface expression and resensitization (and therefore receptor signaling capacity) of ¿2ARs following agonist stimulation and improve responsiveness to ¿-agonists. This improved responsiveness may lead to reduced symptoms in patients with chronic asthma who use ¿-agonists regularly and decreased hospitalizations and deaths from acute asthma exacerbations, where ¿-agonists remain the first-line treatment.

描述（由申请人提供）： 描述：治疗哮喘最常用的药物是激活人β2-肾上腺素能受体（¿2AR）的药物，导致收缩的气道松弛。（¡2AR在细胞上的表面表达。是其响应β激动剂的信号传导能力的关键决定因素。在暴露于激动剂后，大多数¿2AR迅速从细胞表面运输到早期内体。此后，¿2AR 可能被分选至回收途径，从而用重新敏化的受体重新填充细胞表面，或者被转运至溶酶体并在那里被降解（这一过程称为下调）。尽管将 2AR 运输到溶酶体及其随后的下调可能需要受体泛素化，但对早期内涵体水平的步骤知之甚少我们的长期目标是定义调节这些分选步骤的分子机制以及内体如何分选。 2AR 在激动剂触发的脱敏后调节受体的表面表达和再敏化。对于此应用，我们提出以下三个具体目标：（1）确定 Mrs 是否调节快速。 2AR 通过与 Actinin-4/BERP/Myosin Vb 相互作用（从而形成 CART 复合物）实现再循环和再敏化（2）阐明人类 Vps34 相互作用蛋白 rab7 GPTase 在 P2AR 循环调节中的作用； (3). 确定 rab7 相互作用蛋白 XAPC7 是否通过连接蛋白酶体功能和这些目标将通过结合互补的分子、生化和先进的显微技术来实现，所提出的研究将在 HEK293 细胞中进行，并且关键发现将在培养的人气道细胞中得到证实。研究将为治疗干预提供新的目标，以增加 ¿ 的表面表达和再敏化（以及受体信号传导能力） 2ARs 激动剂刺激后并提高对 ¿ 的反应能力-激动剂的这种改善的反应性可能会导致使用 ¿ 的慢性哮喘患者的症状减轻。 - 定期使用激动剂并减少哮喘急性发作导致的住院和死亡，其中 ¿ -激动剂仍然是一线治疗。