Proteasome Regulation of Interleukin-5 Receptor Endocyt*

描述（由申请人提供）：白介素-5 (IL-5) 是一种造血细胞因子，对于特应性和哮喘中嗜酸性粒细胞炎症的病理生理学至关重要。了解消除 IL-5 受体 (IL-5R) 诱导的炎症信号的机制对于开发调节 IL-5 介导的炎症的新方法具有重要意义。本申请的目标是确定通过泛素和蛋白酶体降解途径控制 IL-5R 内化的分子机制。我们的总体假设是，IL-5 诱导的 IL-5R 内化由两种不同的机制调节：泛素/蛋白酶体降解途径和网格蛋白介导的内吞作用。目的 1. 测试蛋白酶体通过首先降解 (c 胞质结构域) 介导连接的 IL-5R 内化的假设。为了确定 (c 胞质结构域的一部分的降解是否是 IL-5R 内化的起始信号，将检查各种胞质截短的 (c 突变体) 介导连接的 IL-5R 的不依赖于蛋白酶体的内化的能力。此外，需要将研究另一种参与细胞因子 IL-3 和 GM-CSF 的 (c 内化) 中的蛋白酶体活性。目标 2. 检验以下假设：IL-5R 通过网格蛋白介导的内吞作用内化，并且受体的内化发生在 (c 细胞质结构域的蛋白酶体降解之前)。将使用抑制网格蛋白介导的内吞作用的两种不同方法来确定 IL-5R 是否通过该机制内化，以及是否IL-5 刺激的 (c 信号传导和蛋白酶体降解发生在 IL-5R 内化后。目标 3. 研究 (c 泛素化在 IL-5R 内化中的功能作用和性质。温度敏感的 ts20 细胞系在泛素结合中具有温度敏感缺陷，所有形式的泛素化都有缺陷的 (c 突变体) 和显性失活泛素亚型将用于检查 (c 泛素化) 的作用和性质。 (c IL-5R 内吞作用中的泛素化。

DESCRIPTION (provided by applicant): Interleukin-5 (IL-5) is a hematopoietic cytokine that is central to the pathophysiology of eosinophilic inflammation in atopy and asthma. Understanding mechanisms that extinguish IL-5 receptor (IL-5R)-induced inflammatory signals has importance for the development of novel approaches to modulate IL-5-mediated inflammation. The goal of this application is to define the molecular mechanisms controlling IL-5R internalization by the ubiquitin and proteasome degradation pathway. Our overall hypothesis is that IL-5-induced IL-5R internalization is regulated by two different mechanisms: the ubiquitin/proteasome degradation pathway and clathrin-mediated endocytosis. Aim 1. Test the hypothesis that proteasomes mediate internalization of the ligated IL-5R by first degrading the (c cytoplasmic domain. To determine if degradation of a portion of the (c cytoplasmic domain is the initiating signal for IL-5R internalization, various cytoplasmically truncated (c mutants will be examined for their ability to mediate proteasome-independent internalization of the ligated IL-5R. In addition, requirement for proteasome activity in (c internalization by the other (c engaging cytokines, IL-3 and GM-CSF, will be investigated. Aim 2. Test the hypothesis that the IL-5R is internalized by clathrin-mediated endocytosis and that internalization of the receptor occurs before proteasome degradation of the (c cytoplasmic domain. Two different approaches that inhibit clathrin-mediated endocytosis will be used to determine if the IL-5R is internalized by this mechanism and if IL-5-stimulated (c signaling and proteasome degradation occur after IL-5R internalization. Aim 3. Investigate the functional role and nature of (c ubiquitination in IL-5R internalization. The temperature sensitive ts20 cell line which has a temperature sensitive defect in ubiquitin conjugation, a (c mutant that is defective in all forms of ubiquitination, and dominant negative ubiquitin isoforms will be used to examine the role and nature of (c ubiquitination in IL-5R endocytosis.