Signaling Cell Death from the Endoplasmic Reticulum

内质网发出细胞死亡信号

• 批准号: 8038302
• 负责人: Scott A. Oakes
• 金额: $ 31.1万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8038302
• 关键词: Adaptor Signaling Protein; Apoptosis; Apoptotic; BAX gene; BCL1 Oncogene; BID protein; Caspase; Cell Death; Cell Death Signaling Process; Cell Survival; Cells; Cellular Stress; Cessation of life; Cleaved cell; Complex; Coupled; Data; Defect; Endoplasmic Reticulum; Environment; Event; Health; Homeostasis; Hypoxia; In Vitro; Laboratories; Lead; Life; Location; Malignant Neoplasms; Mammalian Cell; Mass Spectrum Analysis; Membrane; Mitochondria; Molecular; Molecular Chaperones; Neoplasm Metastasis; Nutrient; Outer Mitochondrial Membrane; Output; Oxygen; Pathway interactions; Process; Protein Family; Proteins; Proto-Oncogenes; Role; SH3 Domains; Sequence Analysis; Signal Pathway; Signal Transduction; Signal Transduction Pathway; Stress; Supporting Cell; Technology; Therapeutic; Translations; Vascular blood supply; accomplished suicide; cancer cell; caspase-2; cytotoxic; deprivation; endoplasmic reticulum stress; in vivo; killings; neoplastic cell; new therapeutic target; novel; pro-caspase-2; programs; protein folding; protein misfolding; response; sensor; src Homology Region 2 Domain; therapeutic target

DESCRIPTION (provided by applicant): Cancer cells must avert apoptotic checkpoints to survive in unfavorable conditions, such as nutrient deprivation and hypoxia, which quickly lead to excessive demand on the protein folding capacity of the endoplasmic reticulum (ER). When the extent of unfolded proteins in the ER lumen reaches a critical level, the cell engages a set of evolutionarily conserved signal transduction pathways that are collectively known as the unfolded protein response (UPR). Major effectors of the UPR in mammalian cells are the ER-resident transmembrane sensors IRE11, PERK, and AFT6. These stress sensors initially expand the ER network, upregulate chaperones and arrest global translation to restore homeostasis. However, if the ER damage is severe, these ER resident stress sensors initiate apoptosis through poorly understood mechanisms. Sustained and high level ER stress is documented in many forms of cancer; hence, malignant cells must evolve mechanisms to evade the normally cytotoxic consequences of such stress. Efforts to restore the apoptotic outputs of the UPR hold promise as a therapeutic strategy to kill cancer cells. Excessive ER stress triggers the "intrinsic" apoptotic pathway, which is tightly regulated at the outer mitochondrial membrane by the pro-death BCL-2 family proteins BAX and BAK. However, the molecular chain of events leading from ER stress to mitochondrial BAX/BAK activation remains poorly understood. My laboratory has developed a process to purify the pre- mitochondrial apoptotic activity from the cytosolic extract of ER-stressed Bax-/-Bak-/- cells. Using this technology, we have identified two major apoptotic signals that converge on mitochondrial BAX/BAK. One signal is the BH3-only protein BID, which is cleaved into its shorter pro-apoptotic form by Caspase-2. We now seek to understand the events that lead from the sensing of misfolding proteins at the ER membrane to the catalytic activation of Caspase-2, one of the most poorly characterized mammalian caspases. From the active extract, we also recently purified a second novel component-an adaptor protein containing an SH2 domain and two SH3 domains, which our data suggest is a BID-independent apoptotic signal downstream of ER stress. We now aim to define the pro-apoptotic role of this adaptor protein in ER stress signaling. The long- term objectives of this proposal are to understand how cells detect ER stress, decide if the damage is lethal, and communicate this information to the cell death machinery, and to identify components in the pathway that can be manipulated to influence cell survival. Two specific aims are outlined: (1) Define the mechanism(s) by which ER stress activates Caspase-2, and (2) Determine the role of this SH2/SH3-containing adaptor protein in ER stress signaling. These studies will define the mechanisms that control apoptosis downstream of ER stress-a pathway that may represent a key therapeutic target in cancer cells. PUBLIC HEALTH RELEVANCE: All cells in our body are genetically programmed to commit suicide through a process called "apoptosis" when exposed to stressful conditions such as low oxygen or scarce blood supply. Defects in this apoptotic pathway allow cancer cells to survive and metastasize to foreign environments where unfavorable conditions would normally trigger death. This projects sets out to define how cellular stress normally leads to apoptosis and what goes wrong with this process in cancer-in the hopes of finding new therapeutic targets through which to kill tumor cells.

描述（由申请人提供）：癌细胞必须避免凋亡检查点在不利条件下（例如营养剥夺和缺氧）生存，这很快导致对内质网（ER）蛋白质折叠能力的需求过高。当ER管腔中展开的蛋白质的程度达到临界水平时，该细胞会与一组进化保守的信号转导途径相连，这些信号转导途径被共同称为展开的蛋白质反应（UPR）。 UPR在哺乳动物细胞中的主要效应因子是ER驻留的跨膜传感器IRE11，PERK和AFT6。这些压力传感器最初扩大了ER网络，上调伴侣并将全球翻译逮捕以恢复体内平衡。但是，如果ER损伤严重，这些ER驻留的压力传感器会通过了解较低的机制引发凋亡。许多形式的癌症记录了持续和高水平的ER压力；因此，恶性细胞必须发展机制，以逃避这种压力的正常细胞毒性后果。恢复UPR的凋亡输出的努力是杀死癌细胞的治疗策略。过度的ER应力会触发“固有”的凋亡途径，该途径受到pro-Death Bcl-2家族蛋白BAX和BAK在线粒体外膜上的严格调节。然而，从ER应力到线粒体BAX/BAK激活导致的事件的分子链仍然尚不清楚。我的实验室已经开发了一个从ER压力Bax的胞质提取物 - / - BAK - / - 细胞中纯化线粒体凋亡活性的过程。使用这项技术，我们已经确定了两个主要的凋亡信号，它们会在线粒体BAX/BAK上汇聚。一个信号是仅BH3的蛋白质出价，它通过caspase-2裂解到其较短的促凋亡形式中。现在，我们试图了解从ER膜上错误折叠蛋白的感知到caspase-2的催化激活的事件，caspase-2是最差的哺乳动物caspase之一。从活跃的提取物中，我们最近还纯化了第二个新型组件 - 含SH2结构域和两个SH3结构域的衔接蛋白，我们的数据表明，这是ER应力下游下游的竞标非依赖性凋亡信号。现在，我们旨在定义该衔接蛋白在ER应力信号传导中的促凋亡作用。该提案的长期目标是了解细胞如何检测ER应力，确定损害是否致命，并将这些信息传达给细胞死亡机器，并在途径中识别可以操纵以影响细胞存活的途径中的组件。概述了两个具体的目的：（1）定义ER应力激活CASPASE-2的机制，（2）确定该含SH2/SH3的适配器蛋白在ER应力信号传导中的作用。这些研究将定义控制ER应力A途径下游凋亡的机制，该途径可能代表癌细胞中的关键治疗靶点。公共卫生相关性：我们体内的所有细胞都经过基因编程，以通过称为“凋亡”的过程自杀，例如氧气低或稀缺的血液供应。这种凋亡途径中的缺陷使癌细胞能够生存并转移到不利条件通常会触发死亡的外国环境中。该项目旨在定义细胞应激如何通常导致凋亡以及此过程中的癌症过程中出了问题，希望找到新的治疗靶标的杀死肿瘤细胞。