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

描述（由申请人提供）：ATR-Chk1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至关重要的作用。ATR-Chk1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（如出芽和裂变酵母）中通路的深入研究。人们对该通路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通路的更专门功能，ATR-Chk1将在后生动物秀丽隐杆线虫中进行研究。在秀丽隐杆线虫胚胎发生过程中，ATR-Chk1以一种谱系特异性的方式控制细胞分裂的时间。支持这一应用的初步数据表明，胚胎发生过程中ATR- chk1通路的激活机制与其他系统中描述的不同，因此Aim 1的目标是确定ATR激活因子并研究其激活机制。目的2旨在了解ATR-Chk1在胚胎发生过程中谱系特异性信号传导的基础。Aim 3研究了ATR- Chk1在生殖系干细胞长期停滞后细胞周期重新进入中的新功能。在秀丽隐杆线虫的生殖系发育过程中，干细胞Z2和Z3在前期阻滞细胞周期，这些细胞一直阻滞到幼虫孵化并开始觅食。支持该应用的初步数据表明，Chk1在细胞周期再进入过程中起着至关重要的作用。Chk1活性的减弱扰乱了再入的时间，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，Aim 3的目标是揭示Chk1这种新功能的分子基础。本研究的成功完成将大大拓宽我们对ATR-Chk1在胚胎和种系发育过程中的功能的理解。这些实验还将深入了解基本细胞周期过程如何与发育和生殖事件相结合。最后，对ATR-Chk1在人类干细胞增殖过程中的功能的深入了解可能会随着这项工作的完成而产生，因为已经确定不对称细胞分裂的基本机制在后生动物中是高度保守的。

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.