Chromatin Degradation During Apoptosis

细胞凋亡过程中染色质降解

• 批准号: 8295703
• 负责人: DING XUE
• 金额: $ 27.21万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8295703
• 关键词: Alzheimer' s Disease; Animal Model; Animals; Apoptosis; Apoptotic; Autoimmune Diseases; Biochemical; Biological; Biological Assay; Biological Process; Caenorhabditis elegans; Calcium; Cancer Etiology; Caspase; Cell Death; Cell Death Signaling Process; Cell Nucleus; Cell physiology; Cells; Chromatin; Chromosomes; Cleaved cell; Complex; DNA; DNA Binding; DNA Double Strand Break; DNA-Binding Proteins; Defect; Deoxyribonucleases; Development; Enzymes; Event; Genes; Genetic; Homeostasis; Homologous Gene; Human; Hydroxyl Radical; Malignant Neoplasms; Mediating; Mitochondria; Molecular; Molecular Cloning; Molecular Genetics; Mutation; Pathway interactions; Peptide Hydrolases; Phosphatidylserines; Process; Pump; RNA Binding; RNA Interference; Regulation; Ribonucleases; Role; Signal Pathway; Signal Transduction; Small RNA; Specificity; Structure; Tissues; Work; base; caspase-3; cell killing; cell suicide; controlled release; genome wide association study; human DICER1 protein; human disease; in vitro Assay; in vivo; insight; interest; mutant; new therapeutic target; novel; nuclease; presenilin; prevent; ubiquilin

DESCRIPTION (provided by applicant): Fragmentation of chromosomal DNA is a critical step in apoptosis that prevents a cell from transcribing and replicating its genes and thus facilitates the cell killing process. Defects in this process can cause various pathological conditions, including autoimmune disorders and cancer. We have identified ten apoptotic nucleases and several non-nuclease factors involved in regulating and executing apoptotic chromosome fragmentation in C. elegans. They act in a sequential and CED-3 caspase-dependent manner to promote stepwise fragmentation and degradation of chromosomes. The process is initiated by a novel CED-3-mediated conversion of the dicer ribonuclease (RNase) into a deoxyribonuclease (DNase), which makes the first cuts on chromosomes. In parallel, a mitochondrial nuclease CPS-6 and its activator WAH-1 are released from mitochondria and translocated to the nucleus, where they interact and cooperate with other cell death nucleases to turn the initial cuts by dicer into double-strand DNA breaks, leading to fragmentation and degradation of chromosomes. In this proposed work, we will carry out molecular genetic, biochemical, cell biological, and structural analyses to understand these two critical events of apoptotic DNA degradation. In Aim 1, we will investigate the molecular and structural basis underlying CED-3-mediated conversion of the dicer RNase into a DNase. In Aim 2, we will dissect the new signaling pathway that controls cytosolic calcium increase and release of the mitochondrial apoptogeneic factors during apoptosis. In Aim 3, we will perform molecular genetic and functional characterization of two new genes, cps-13 and cps-14, that regulate and coordinate two key cell death execution events, chromosome fragmentation and phosphatidylserine (PS) externalization. These studies should reveal the novel mechanism that controls the specificity and function switch of the dicer nuclease and new signaling mechanisms and players that control the release of the mitochondrial apoptogenic factors. PUBLIC HEALTH RELEVANCE: Fragmentation of chromosomal DNA is a critical step in apoptosis, a cell suicide process that could go awry to cause multiple human diseases. Defects in apoptotic chromosome fragmentation can cause various pathological conditions, including autoimmune disorders and cancer. C. elegans is an excellent animal model for studying basic mechanisms of apoptosis and apoptotic chromosome fragmentation. This proposal seeks to understand the mechanisms that regulate activation of apoptotic nucleases and release of apoptosis factors from mitochondria through important signaling pathways. The studies may identify new genes, pathways, and mechanisms that regulate and execute apoptosis, leading to identification of new therapeutic targets or ideas to treat human disease such as Alzheimer's disease, autoimmune disorders, and cancer that are caused by abnormal apoptosis or DNA degradation.

描述（由申请人提供）：染色体 DNA 的断裂是细胞凋亡的关键步骤，它阻止细胞转录和复制其基因，从而促进细胞杀伤过程。这一过程的缺陷可能导致各种病理状况，包括自身免疫性疾病和癌症。我们已经鉴定了秀丽隐杆线虫中参与调节和执行凋亡染色体断裂的十种凋亡核酸酶和几种非核酸酶因子。它们以顺序且依赖 CED-3 caspase 的方式发挥作用，促进染色体逐步断裂和降解。该过程由新型 CED-3 介导的切丁核糖核酸酶 (RNase) 转化为脱氧核糖核酸酶 (DNase) 启动，这在染色体上进行了第一次切割。与此同时，线粒体核酸酶 CPS-6 及其激活剂 WAH-1 从线粒体中释放出来并转移到细胞核，在那里它们与其他细胞死亡核酸酶相互作用并配合，以转变切丁机的初始切割 导致双链 DNA 断裂，导致染色体断裂和降解。在这项拟议的工作中，我们将进行分子遗传学、生化、细胞生物学和结构分析，以了解细胞凋亡 DNA 降解的这两个关键事件。在目标 1 中，我们将研究 CED-3 介导的切丁机 RNase 转化为 DNase 的分子和结构基础。在目标 2 中，我们将剖析细胞凋亡过程中控制胞浆钙增加和线粒体凋亡因子释放的新信号通路。在目标 3 中，我们将对两个新基因 cps-13 和 cps-14 进行分子遗传学和功能表征，这两个基因调节和协调两个关键的细胞死亡执行事件：染色体断裂和磷脂酰丝氨酸 (PS) 外化。这些研究应该揭示控制切丁核酸酶特异性和功能转换的新机制以及控制线粒体凋亡因子释放的新信号机制和参与者。 公共卫生相关性：染色体 DNA 碎片是细胞凋亡的关键步骤，细胞凋亡是一种细胞自杀过程，如果出错，可能会导致多种人类疾病。凋亡染色体断裂的缺陷可导致各种病理状况，包括自身免疫性疾病和癌症。线虫是研究细胞凋亡和细胞凋亡染色体断裂基本机制的优秀动物模型。该提案旨在了解通过重要信号通路调节凋亡核酸酶激活和线粒体释放凋亡因子的机制。这些研究可能会发现调节和执行细胞凋亡的新基因、途径和机制，从而确定新的治疗靶点或想法来治疗人类疾病，如阿尔茨海默病、自身免疫性疾病和由异常细胞凋亡或 DNA 降解引起的癌症。