BIOSYNTHESIS AND DEGRADATION OF IP3 RECEPTORS

IP3 受体的生物合成和降解

基本信息

批准号：
6490242
负责人：
SURESH K JOSEPH
金额：
$ 28.85万
依托单位：
THOMAS JEFFERSON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-01-01 至 2003-12-31
项目状态：
已结题

项目摘要

Ca2+ mobilization from internal stores is important in the acute regulation of cell metabolism and in regulating key steps in cell growth, cell division and programmed cell death. Binding of the intracellular messenger D-myo-Inositol 1,4,5-trisphosphate (IP3) by a specific receptor/Ca2+ ion channel (IP3R) mediates the mobilization of Ca2+ from intracellular stores. Although the structural and functional aspects of this receptor are under active investigation, there has been no systematic study of the biosynthesis and degradation of this class of important intracellular ion-channels and this represents the focus of this grant proposal. Our initial studies have shown that chronic treatment of WB cells with the Ca2+ mobilizing agonist Angiotensin II causes down-regulation of IP3R isoforms by activating the ubiquitin/proteasome pathway. We have also identified selective interactions of nascent IP3R isoforms with the Ca2+-binding molecular chaperones calnexin and calreticulin. These studies will be extended using several experimental models including cultured cells, cell-free translation systems and expression of specific IP3R cDNAs in transfected cells. The specific aims of this proposal are: [1]. To characterize early steps in the assembly of IP3Rs - The kinetics and mechanism of oligomerization will be studied. [2]. To study the association of IP3Rs with molecular chaperones - The consequences of chaperone association for IP3R assembly and function will be assessed. [3].To characterize the structural features of IP3R isoforms that are important for regulated degradation - Mutant IP3Rs will be tested as degradation substrates in various model systems. [4]. To define the role of the ubiquitin/proteasome pathway in the regulated turnover of IP3R - The regulation of proteasomal activity in ER membranes will be investigated. Our long-term goal is to understand the factors that regulate the levels of individual IP3R isoforms. The proposed studies are also intended to provide fundamental insights into the mechanisms of ion-channel assembly and the regulated degradation of polytopic membrane proteins in the endoplasmic reticulum.

内部商店的CA2+动员在细胞代谢的急性调节以及调节细胞生长，细胞分裂和程序性细胞死亡的关键步骤中很重要。特定受体/Ca2+离子通道（IP3R）的细胞内信使D-myositol 1,4,5-三磷酸（IP3）的结合介导了细胞内存储中Ca2+的动员。尽管该受体的结构和功能方面正在积极研究中，但尚无对这类重要细胞内离子通道的生物合成和降解的系统研究，这代表了该赠款建议的重点。我们的最初研究表明，用Ca2+动员激动剂血管紧张素II对WB细胞的慢性治疗通过激活泛素/蛋白酶体途径，从而导致IP3R同工型的下调。我们还确定了新生IP3R同工型与Ca2+结合分子伴侣clnexin和钙网蛋白的选择性相互作用。这些研究将使用几个实验模型进行扩展，包括培养细胞，无细胞的翻译系统以及转染细胞中特定IP3R cDNA的表达。该提案的具体目的是：[1]。为了表征IP3RS组装的早期步骤 - 将研究寡聚化的动力学和机制。 [2]。为了研究IP3RS与分子伴侣的关联 - 将评估伴侣伴侣协会在IP3R组装和功能方面的后果。 [3]。要表征IP3R同工型的结构特征，这些特征对于调节的降解很重要 - 突变体IP3RS将被测试为各种模型系统中的降解底物。 [4]。为了定义泛素/蛋白酶体途径在IP3R的调节周转中的作用 - 将研究ER膜中蛋白酶体活性的调节。我们的长期目标是了解调节单个IP3R同工型水平的因素。拟议的研究还旨在提供有关离子通道组件机制以及内质网中多重膜蛋白的调节降解的基本见解。