MECHANISM OF ANTI-APOPTOTIC FUNCTION OF GRP78/BiP

GRP78/BiP的抗凋亡作用机制

• 批准号: 7235324
• 负责人: AMY S LEE
• 金额: $ 27万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7235324
• 关键词: Address; Affect; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein; Apoptosis; Apoptosis Regulator; Apoptotic; BAK1 gene; BAX gene; BCL2-Interacting Killer; BIK gene; Bax protein; Binding; Biological Assay; Brain; Breast Cancer Cell; Cancer Model; Cancer cell line; Cancerous; Caspase; Cell Death; Cells; Cellular biology; Complex; Cultured Cells; DNA Damage; Disruption; Drug resistance; Embryo; Endoplasmic Reticulum; Endothelial Cells; Epithelial Cells; Estrogen Antagonists; Etoposide; Fibroblasts; GRP78 gene; Genes; Genetic; Glioma; Glucose; Hand; Homeostasis; Human; Hypoxia; Integral Membrane Protein; Knockout Mice; Knowledge; Link; Localized; MAPK8 gene; Malignant Neoplasms; Mediating; Membrane; Messenger RNA; Mitochondria; Modeling; Molecular; Molecular Chaperones; Mus; Nerve Degeneration; Neuroblastoma; Neurodegenerative Disorders; Noxae; Organelles; Parkinson Disease; Pathway interactions; Patients; Personal Satisfaction; Physiological; Play; Prevention; Prion Diseases; Protein Family; Protein Overexpression; Proteins; Puma; Rate; Regulation; Research Personnel; Resistance; Role; Signal Transduction; Signaling Molecule; Site; Small Interfering RNA; Solid Neoplasm; Stimulus; Stress; Technology; Testing; Tissues; Topoisomerase Inhibitors; Topoisomerase-II Inhibitor; Toxic effect; Transcript; Translating; Vascularization; Work; apoptotic protease-activating factor 1; base; cancer cell; caspase-9; chemotherapeutic agent; clinically relevant; cytochrome c; in vivo; inhibitor/antagonist; novel; programs; response; tumor

DESCRIPTION (provided by applicant): While it is well-established that the endoplasmic reticulum (ER) plays a critical role in cellular homeostasis, its significant contribution to apoptosis is only now becoming apparent. This proposal aims at discovering the molecular mechanisms of the ER stress-induced apoptosis and of the antiapoptotic function of ER chaperone protein GRP78/BJP. We hypothesize that the ER stress-induced apoptosis initiates from the ER but is amplified through the mitochondria via multiple pathways and that one anti-apoptotic function of GRP78 relies on its prevention of activation of pro-apoptotic components that initiate the cell death program from the ER. Our hypothesis is based on the recent discovery that the ER is a site of convergence and regulation of both pro- and anti-apoptotic components, and that GRP78, a key regulator of the unfolded protein response, can protect cells against apoptosis induced by ER stress as well as DNA-damaging topoisomerase inhibitors. Further, GRP78 can exist as a transmembrane protein and interact with caspases inducible by ER stress or etoposide and block their activation. Towards understanding the underlying in vivo molecular mechanisms, we have three specific aims. In Aim 1, through the use of Apaf-1 deficient and BAX/BAK double knock MEFs, we will assess the requirement of the mitochondrial branch for ER-initiated apoptotic pathways, the relationship between known ER apoptotic pathways and ER BAK/BAX activation. We will further identify the molecules linking ER stress to activation of mitochondrial apoptotic pathway and their induction mechanism by ER stress. In Aim 2, we will identify steps of the ER-stress and etoposide-induced apoptotic pathway that is suppressed by GRP78 and test whether GRP78 is a novel inhibitor of BIK, an upstream regulator of BAX. In Aim 3, we will determine whether the ER stress-induced apoptotic pathways are altered in cancer, and the cytoprotective function of GRP78 in amyloid-beta toxicity in neuroblastoma and endothelial cells within tumors. The proposed work will not only contribute novel information on basic cell biology but also has clinical relevance in eliminating drug-resistant cancers and neurodegeneration in patients.

描述（由申请人提供）：虽然内质网（ER）在细胞稳态中发挥着关键作用这一点已得到充分证实，但其对细胞凋亡的重要贡献现在才变得明显。本研究旨在揭示内质网应激诱导细胞凋亡的分子机制以及内质网伴侣蛋白GRP78/BJP的抗凋亡功能。我们假设内质网应激诱导的细胞凋亡始于内质网，但通过多种途径通过线粒体放大，并且 GRP78 的一种抗凋亡功能依赖于其阻止促凋亡成分的激活，而促凋亡成分可从内质网启动细胞死亡程序。我们的假设基于最近的发现，即内质网是促凋亡和抗凋亡成分的汇聚和调节部位，而 GRP78 是未折叠蛋白反应的关键调节因子，可以保护细胞免受内质网应激以及 DNA 损伤性拓扑异构酶抑制剂诱导的细胞凋亡。此外，GRP78 可以作为跨膜蛋白存在，并与 ER 应激或依托泊苷诱导的半胱天冬酶相互作用，并阻止其激活。为了了解潜在的体内分子机制，我们有三个具体目标。在目标 1 中，通过使用 Apaf-1 缺陷和 BAX/BAK 双敲入 MEF，我们将评估线粒体分支对 ER 启动的凋亡途径的需求、已知的 ER 凋亡途径与 ER BAK/BAX 激活之间的关系。我们将进一步鉴定将内质网应激与线粒体凋亡途径激活联系起来的分子及其通过内质网应激的诱导机制。在目标 2 中，我们将确定 GRP78 抑制的 ER 应激和依托泊苷诱导的细胞凋亡途径的步骤，并测试 GRP78 是否是 BAX 上游调节剂 BIK 的新型抑制剂。在目标 3 中，我们将确定癌症中 ER 应激诱导的细胞凋亡途径是否发生改变，以及神经母细胞瘤和肿瘤内皮细胞中淀粉样蛋白 β 毒性中 GRP78 的细胞保护功能。拟议的工作不仅将提供有关基础细胞生物学的新信息，而且在消除患者的耐药癌症和神经退行性疾病方面具有临床意义。