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

描述(申请人提供)：ATR-Chk1信号通路在细胞周期控制和细胞对复制压力的反应中发挥关键作用。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或更简单的生物(如发芽和分裂酵母)的同源群体中该途径的深入研究。对该途径在动物发育和繁殖中的功能(S)了解较少，因此为了更深入地了解该途径更专门的功能，我们将在后生动物线虫中研究ATR-Chk1。在线虫胚胎发育过程中，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，ATR-Chk1途径在胚胎发育过程中的激活机制与其他系统中所描述的不同，因此目标1的目标是识别ATR激活剂并研究其激活机制。目的2试图了解ATR-Chk1在胚胎发育过程中的谱系特异性信号基础。目的3研究ATR-Chk1在生殖系干细胞长期停滞后重新进入细胞周期的新功能。在线虫的生殖系发育过程中，干细胞Z2和Z3将细胞周期停滞在前期，并保持停滞状态，直到幼虫孵化并开始取食。支持这一应用的初步数据表明，Chk1在细胞周期重入过程中起着至关重要的作用。Chk1活性的减弱扰乱了重返大气层的时间，导致DNA损伤，并最终杀死这些生殖系干细胞，导致动物不育。因此，目标3的目标是揭示Chk1这一新功能的分子基础。本申请中提出的工作的成功完成将极大地拓宽我们对ATR-Chk1在胚胎和生殖系发育中的功能的理解。这些实验还将深入了解基本的细胞周期过程是如何与发育和生殖事件相结合的。最后，这项工作的完成可能有助于深入了解ATR-Chk1在人类干细胞增殖中的作用，因为众所周知，不对称细胞分裂的基本机制在后生动物中高度保守。 公共卫生相关性：ATR-Chk1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变得癌症方面发挥关键作用。因此，深入了解ATR-Chk1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-Chk1在模式生物--线虫中的机制和功能，重点是ATR-Chk1在胚胎发育和生殖生殖细胞形成中的新功能。

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.