Novel Roles for Effector Procaspases

效应器蛋白酶原的新作用

• 批准号: 8896823
• 负责人: Lawrence H. Boise
• 金额: $ 29.64万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8896823
• 关键词: Actins; Adaptor Signaling Protein; Adherence; Adhesions; Anoikis; Apoptosis; Apoptotic; Aspartate Ammonia-Lyase; Aspartic Acid; Caspase; Caspase-1; Cell Adhesion; Cell Death; Cell Death Process; Cell Proliferation; Cell Survival; Cell membrane; Cell physiology; Cell-Cell Adhesion; Cells; Cellular Morphology; Cleaved cell; Complex; Cues; Cysteine; Cytoskeletal Modeling; Cytoskeleton; Cytosol; Data; Dendritic Spines; Development; Disease; Disseminated Malignant Neoplasm; Drosophila genus; Embryo; Embryonic Development; Enzyme Precursors; Erythrocytes; Eukaryotic Cell; Event; Extracellular Matrix; Feedback; Fibroblasts; Fibronectins; Forms Controls; Health; Immune response; Infection; Inflammatory; Inflammatory Response; Length; Lens Fiber; Light; Mitochondria; Modeling; Morphology; Mus; Necrosis; Occupations; Phenotype; Play; Process; Proteins; Regulation; Research; Role; Signal Transduction; Stress; Structure; Subgroup; Synaptic plasticity; T-Lymphocyte; Therapeutic; Virus; Wound Healing; base; caspase-3; caspase-7; caspase-8; cell killing; cell motility; cytochrome c; cytokine; design; dimer; feeding; fiber cell; migration; mitochondrial dysfunction; mutant; novel; response; sperm cell

DESCRIPTION (provided by applicant): Caspases are cysteine aspartases found in all eukaryotic cells as zymogens that require induced proximity and/or proteolytic cleavage for activation. Activated caspases function as both regulators and executioners of cell death in response to developmental cues or environmental stress (e.g. apoptosis) and infections (e.g. pyroptosis and necroptosis). Activated caspases can have equally profound systemic effects by controlling inflammatory responses through cytokine maturation as well as induction of cell proliferation and migration in the wound-healing response (e.g. the "phoenix rising" phenomena). Therefore there has been a significant amount of research on the mechanism of caspase activation and the function of active caspases since aberrant activation could have catastrophic consequences for the cell. It has long been presumed that the zymogens of caspases (procaspases) had no function and were only present to allow for a quick and decisive means for a cell to induce cell death or an inflammatory response. While studying the role of the effector caspases-3 and -7 on mitochondrial function following cytochrome c release, we serendipitously discovered novel functions for procaspase-3 and procaspase-7 that shed new light on why cells carry killer molecules. Mouse embryo fibroblasts (MEFs) that are deficient in casp3 display enhanced adhesion and altered migration velocity that is associated with increased fibronectin secretion. Introduction of procaspase-3 or a procaspase-3 that is catalytically inactive reverses this phenotype. Casp7-deficient MEFs have altered morphology and loss of directionally-persistent migration. These events appear to be associated with altered actin cytoskeleton organization and are also independent of caspase activity. Thus effector procaspases are not only poised killer molecules, they have cellular functions in viable cells. The first two Specific Aims of this application are designed to determine how these effector procaspases regulate cell adhesion, migration and secretion. Additionally we have found that the survival advantage observed with casp3-deficient MEFs is dependent on cell adhesion. Casp3-deficient cells are not protected against loss of adherence to extracellular matrix (anoikis). This suggests that the non-apoptotic functions of procaspase-3 can also influence the cellular response to apoptotic signals. This would have a significant impact on current models of feed-forward loops that have been proposed to explain how an effector caspase could influence events that occur upstream of caspase activation. Therefore the final Specific Aim of this application will re-examine the mechanism by which loss of casp3 alters cell survival. Completion of these Aims will have a paradigm-shifting effect on how we think about procaspases and may require a re-interpretation of data generated with caspase-deficient cells.

描述（由申请人提供）：半胱天冬酶是在所有真核细胞中作为酶原发现的半胱氨酸天冬氨酸酶，需要诱导接近和/或蛋白水解裂解来激活。激活的半胱天冬酶作为细胞死亡的调节者和执行者，响应发育线索或环境应激（例如细胞凋亡）和感染（例如细胞焦亡和坏死性凋亡）。活化的半胱天冬酶可以通过细胞因子成熟控制炎症反应以及在伤口愈合反应中诱导细胞增殖和迁移（例如“凤凰涅槃”现象）来产生同样深远的全身效应。因此，对于 caspase 激活机制和活性 caspase 的功能进行了大量研究，因为异常激活可能会给细胞带来灾难性后果。长期以来，人们一直认为半胱天冬酶（半胱天冬酶原）的酶原没有任何功能，其存在只是为了让细胞能够快速而决定性地诱导细胞死亡或炎症反应。在研究细胞色素 c 释放后效应器 caspase-3 和 -7 对线粒体功能的作用时，我们偶然发现了 procaspase-3 和 procaspase-7 的新功能，为细胞携带杀伤分子的原因提供了新的线索。缺乏 casp3 的小鼠胚胎成纤维细胞 (MEF) 显示出粘附力增强和迁移速度改变，这与纤连蛋白分泌增加相关。引入 procaspase-3 或催化失活的 procaspase-3 可逆转这种表型。 Casp7 缺陷的 MEF 改变了形态并丧失了定向持续迁移。这些事件似乎与肌动蛋白细胞骨架组织的改变有关，并且与半胱天冬酶活性无关。因此，效应蛋白半胱氨酸蛋白酶原不仅是蓄势待发的杀伤分子，它们在活细胞中也具有细胞功能。本申请的前两个具体目标旨在确定这些效应子天冬酶原如何调节细胞粘附、迁移和分泌。此外，我们发现 casp3 缺陷 MEF 的生存优势取决于细胞粘附。 Casp3 缺陷细胞无法防止细胞外基质粘附丧失（失巢凋亡）。这表明 procaspase-3 的非凋亡功能也可以影响细胞对凋亡信号的反应。这将对当前的前馈循环模型产生重大影响，该模型已被提出来解释效应器 caspase 如何影响 caspase 激活上游发生的事件。因此，本申请的最终具体目标将重新检查 casp3 丢失改变细胞存活的机制。这些目标的完成将对我们如何看待 caspase 前体产生范式转变的影响，并且可能需要重新解释 caspase 缺陷细胞生成的数据。