Proteostasis at cellular membranes

项目摘要 细胞膜不仅分隔了细胞内的过程，而且还充当了 许多多蛋白信号复合体、癌蛋白和肿瘤抑制因子的组装。因此，a 目前的大多数疗法(60%)以膜蛋白为靶点，膜蛋白约占人体的23% 蛋白质组。对环境提示和药物的响应，细胞内的蛋白质补体 改变膜以安装校准的响应，如果受到扰动，则影响疾病状态，例如， 癌症、心脏和神经疾病。泛素-蛋白酶体系统(UPS)非常适合快速完成这项任务 调节蛋白质以无与伦比的精确度周转。到目前为止，我们对分子细节的理解 膜蛋白周转是如何通过UPS介导的蛋白分解来调节的，目前还不清楚。 我们正在进行UPS调控的新型蛋白质降解的机制研究 膜上的通路模拟了我们之前对Fbxl2的研究，Fbxl2是一种高度保守的F-box蛋白 含有一个典型的C-末端CAAX预烯基化基序，用于定位到细胞膜。正直的 CAAX基序是Fbxl2组装成有活性的SCF泛素连接酶复合体并相互作用所必需的 在细胞膜上有两种底物，P85β和IP3R3。有趣的是，我们最近发现了GGtase3，一个 新的哺乳动物异丙苯基转移酶及鉴定的Fbx12-泛素连接酶作为其生理作用靶点 GGTase3的戊烯基化反应。这项提案使用跨学科的方法来调查监管和 UPS膜锚定蛋白周转与哺乳动物细胞存活和死亡的生物学相关性 并对GGtase3生物学特性进行了研究。

Project Summary Cellular membranes not only compartmentalize intracellular processes but also serve as the dynamic hubs for the assembly of many multi-protein signaling complexes, oncoproteins, and tumor suppressors. Accordingly, a majority of current therapeutics (>60%) target membrane proteins that make up approximately 23% of human proteome. In response to environmental cues and pharmacological drugs, the protein complement of cellular membranes is altered to mount a calibrated response, which, if perturbed, impacts the disease state, e.g., cancer, cardiac and neurological disorders. The ubiquitin-proteasome system (UPS) aptly fits the task to swiftly turnover the regulatory proteins with unmatched precision. To date, our understanding of the molecular details of how membrane protein turnover is regulated by UPS-mediated proteolysis remain sketchy. We are conducting the mechanistic studies in the investigations of novel UPS-regulated protein degradation pathways at membranes modeled on our previous work with FBXL2, a highly conserved F-box protein containing a typical C-terminal CaaX prenylation motif for localization to cellular membranes. The integrity of the CaaX motif is necessary for FBXL2 to assemble into an active SCF ubiquitin ligase complex and interact with two substrates, p85β and IP3R3, at cellular membranes. Interestingly, we recently discovered GGtase3, a new mammalian prenyltransferase and identified FBXL2-ubiquitin ligase as the physiological target for prenylation by GGTase3. This proposal uses an interdisciplinary approach to investigate the regulation and biological relevance of membrane anchored protein turnover by UPS in mammalian cell survival and proliferation, and full characterization of GGtase3 biology.