Chromatin Degradation and Cell Clearance During Apoptosis

描述(申请人提供)：作为动物发育和组织动态平衡的一个正常方面，细胞凋亡通过反对不受控制的细胞增殖，在维持适当细胞数量的生理平衡方面起着至关重要的作用。细胞凋亡的异常失活或激活可导致细胞生长失控或细胞死亡失控，并可能导致癌症、神经退行性疾病和自身免疫性疾病等人类疾病。这项应用的广泛和长期目标是了解控制和执行细胞凋亡的基本机制，并利用这些研究的知识开发新的方法来治疗和预防与细胞凋亡相关的人类疾病，特别是癌症。染色体碎裂是细胞凋亡的标志，也是细胞死亡执行的关键步骤。在细胞凋亡过程中，一组核酸酶被激活，并协同和顺序地促进染色体DNA的碎裂。已在线虫中发现了7个新的细胞死亡相关核酸酶(CRN核酸酶)，它们至少作用于两条不同的途径和两个不同的功能部位，促进DNA降解和清除细胞凋亡。这项应用的目的是在线虫中进行生化、分子遗传学和细胞生物学研究，以剖析DNA凋亡的降解机制，并揭示调控DNA降解和清除凋亡细胞的基本分子机制。其具体目标是：1)对线虫CRN基因进行生化、分子遗传学和功能分析，以了解它们如何协同作用促进DNA凋亡的降解；2)确定和表征其他与DNA凋亡降解有关的重要基因；3)研究染色体碎裂过程如何影响凋亡细胞的清除，这是另一个关键的细胞死亡执行事件，涉及组织重塑、抑制炎症和免疫反应的调节。对细胞凋亡过程中调节染色质降解和细胞清除的分子组成和生化机制的研究将为细胞死亡的执行提供重要的见解，并有助于从总体上理解调控细胞凋亡的基本机制。

DESCRIPTION (provided by applicant): As a normal aspect of animal development and tissue homeostasis, apoptosis plays an essential role in maintaining the physiological balance of appropriate cell numbers by opposing uncontrolled cell proliferation. Abnormal inactivation or activation of apoptosis can lead to uncontrolled cell growth or uncontrolled cell death and may result in human diseases such as cancer, neurodegenerative diseases, and autoimmune disorders. The broad and long-term objectives of this application are to understand the basic mechanisms underlying the control and execution of apoptosis and to use knowledge from such studies to develop new methods to treat and prevent apoptosis-related human diseases, especially caner. Chromosome fragmentation is a hallmark of apoptosis and a critical step in cell death execution. During apoptosis, a battery of nucleases are activated and act cooperatively and sequentially to promote fragmentation of chromosomal DNA. Seven new cell death-related nucleases (CRN nucleases) have been identified in C. elegans and found to act in at least two distinct pathways and two different functioning sites to promote DNA degradation and clearance of apoptotic cells during apoptosis. The goal of this application is to carry out biochemical, molecglar genetic, and cell biological studies in C. elegans to dissect the apoptotic DNA degradation machinery and to unravel the basic molecular mechanisms that regulate the execution of apoptotic DNA degradation and clearance of apoptotic cells. The specific aims are: 1) to carry out biochemical, molecular genetic, and functional analyses of C. elegans crn genes to understand how they work together to promote apoptotic DNA degradation; 2) to identify and characterize additional genes that are important for apoptotic DNA degradation; 3) to investigate how the chromosome fragmentation process affects clearance of apoptotic cells, another critical cell death execution event involved in tissue remodeling, suppression of inflammation, and regulation of immune reponses. The studies of the molecular components and biochemical mechanisms that regulate chromatin degradation and cell clearance during apoptosis will provide crucial insights into how cell death is executed and should contribute to the understanding of the basic mechanisms that regulate apoptosis in general.