ATR-Chk1 signaling during embryonic and germ line development in C. elegans

描述（由申请人提供）：ATR-Chk 1信号通路在细胞周期控制和细胞对复制应激的反应中起着关键作用。ATR-Chk 1功能的机制基础开始被理解，这在很大程度上要归功于对人类组织培养细胞的同质群体或更简单的生物体（如芽殖酵母和裂殖酵母）中的途径的深入研究。对该途径在动物发育和繁殖中的功能了解较少，因此为了更深入地了解该途径的更专门功能，将在后生动物蛔虫C中研究ATR-Chk 1。优雅在C.在线虫胚胎发生中，ATR-Chk 1以谱系特异性方式控制细胞分裂的时间。支持本申请的初步数据表明，在胚胎发生过程中ATR-Chk 1通路的激活通过与其他系统中描述的不同的机制发生，因此目的1的目标是鉴定ATR激活剂并研究激活机制。目的2旨在了解胚胎发生过程中ATR-Chk 1的谱系特异性信号传导的基础。目的3检测ATR-Chk 1在生殖系干细胞长期停滞后重新进入细胞周期中的新功能。在C.在线虫中，干细胞Z2和Z3将细胞周期阻滞在前期，并且这些细胞保持被阻滞，直到幼虫孵化并开始进食。支持这一应用的初步数据表明，Chk 1在细胞周期重新进入过程中起着至关重要的作用。Chk 1活性的减弱扰乱了再进入的时间，导致DNA损伤，并最终杀死这些生殖系干细胞，使动物不育。因此，目标3的目标是揭示Chk 1这种新功能的分子基础。成功完成本申请中提出的工作将显着拓宽我们对胚胎和生殖系发育过程中ATR-Chk 1功能的理解。这些实验还将提供洞察基本细胞周期过程如何与发育和生殖事件相结合。最后，深入了解ATR-Chk 1在人类干细胞增殖过程中的功能可能会导致完成这项工作，因为它是公认的，不对称细胞分裂的基本机制是高度保守的整个后生动物。 公共卫生相关性：ATR-Chk 1信号转导通路在维持基因组稳定性和防止细胞积累突变从而癌变方面发挥关键作用。因此，彻底了解ATR-Chk 1的功能和机制对于更全面地了解癌症生物学至关重要。本项目将研究ATR-Chk 1在模式生物-蛔虫C中的机制和功能。elegans，重点放在新功能ATR-Chk 1在胚胎发育和生殖生殖细胞的形成。

DESCRIPTION (provided by applicant): The ATR-Chk1 signaling pathway plays crucial roles in cell cycle control and in the cellular response to replication stress. The mechanistic basis for ATR-Chk1 function is beginning to be understood, thanks largely to intensive study of the pathway in homogenous populations of human tissue culture cells, or simpler organisms such as budding and fission yeasts. Less well understood are the pathway's function(s) in the development and reproduction of animals, and thus to gain a deeper understanding of more specialized functions of this pathway, ATR-Chk1 will be investigated in the metazoan roundworm C. elegans. During C. elegans embryogenesis, ATR-Chk1 controls the timing of cell division in a lineage-specific manner. Preliminary data in support of this application suggest that activation of the ATR-Chk1 pathway during embryogenesis occurs via a different mechanism than has been described in other systems, and thus the goal of Aim 1 is to identify ATR activators and to study the activation mechanism. Aim 2 seeks to understand the basis for lineage-specific signaling of ATR-Chk1 during embryogenesis. Aim 3 examines a novel function for ATR- Chk1, in cell cycle re-entry after long-term arrest in germ line stem cells. During germ line development in C. elegans, the stem cells Z2 and Z3 arrest the cell cycle at prophase, and these cells remain arrested until the larva hatches and begins to feed. Preliminary data in support of this application demonstrate that Chk1 plays a crucial role during the cell cycle re-entry process. Attenuation of Chk1 activity perturbs the timing of reentry, causes DNA damage, and ultimately kills these germ line stem cells, rendering the animal sterile. The goal of Aim 3 is thus to uncover the molecular basis for this novel function of Chk1. Successful completion of the work proposed in this application will significantly broaden our understanding of ATR-Chk1 function during embryonic and germ line development. These experiments will also provide insight into how basic cell cycle processes are integrated with developmental and reproductive events. Finally, insight into ATR-Chk1 function during human stem cell proliferation will likely result from completion of this work, as it is well established that the basic mechanism of asymmetric cell division is highly conserved throughout metazoans. PUBLIC HEALTH RELEVANCE: The ATR-Chk1 signal transduction pathway play a critical role in maintaining genome stability and in preventing cells from accumulating mutations and thereby becoming cancerous. A thorough understanding of ATR-Chk1 function and mechanism is therefore crucial for a more complete understanding of cancer biology. This project will address ATR-Chk1 mechanism and function in a model organism, the round worm C. elegans, with an emphasis placed on novel functions for ATR-Chk1 during embryonic development and in formation of reproductive germ cells.