Elucidating the Rad51-independent pathway of recombination-dependent replication

在细胞分裂之前，它必须首先复制它的遗传物质，以便每个新的子细胞都能得到一份拷贝。实现这一壮举的DNA复制过程依赖于称为复制体的复杂的多蛋白质机器，复制体在称为复制起点的染色体位置组装到DNA上。这些机器解开DNA双螺旋，形成“叉”结构，在那里复制发生。在细胞周期中，沿着每条染色体的多个起始点“发射”，每个起始点释放一对“复制叉”，它们从起始点向相反的方向移动。DNA复制完成时，分叉从相邻的起源合并。即使是一对分叉的合并失败，也会导致一个未复制的DNA区域出现，从而导致DNA断裂，最终导致基因突变，导致癌症等疾病。DNA损伤和许多结合染色体DNA的蛋白质，通过物理上阻碍复制叉的进展，威胁到复制的成功完成。当一个复制叉遇到这样的屏障时，它可以经历一个称为叉崩溃的过程，在这个过程中，它的复制体部分或完全与DNA分离。为了确保在细胞周期中DNA复制的成功完成，真核细胞使用两种替代的酶途径来修复和重新启动与屏障碰撞后崩溃的复制叉。该项目的目标是了解这些重启途径是如何工作的，重点关注这两个途径中最不为人所知的，这与促进癌细胞存活有关。我们将确定途径的组成部分，并研究它们是如何起作用的。为了实现这些目标，我们将利用一个简单模型真核生物的遗传可追溯性。然而，将要研究的生物学的基本方面是高度保守的，因此，我们的发现将为指导未来的人类细胞研究提供一个有价值的范例。最终，我们的工作将有助于更好地理解复制重启，这对指导新型癌症疗法的发展至关重要。

Before a cell can divide, it must first replicate its genetic material so that each new daughter cell can receive a copy. The DNA replication process that achieves this feat depends on complex multi-protein machines called replisomes, which are assembled onto DNA at chromosomal sites known as replication origins. These machines unwind the DNA double helix to form "fork" structures, at which the copying occurs. During the cell cycle, multiple origins along every chromosome "fire", each releasing a pair of "replication forks" that travel in opposite directions away from their origin. DNA replication is completed when forks from adjacent origins merge. The failure of even a single pair of forks to merge results in a region of unreplicated DNA that can lead to DNA breakage, and ultimately genetic mutations that cause diseases such as cancer. DNA lesions, and the many proteins that bind chromosomal DNA, threaten successful completion of replication by physically impeding the progress of the replication fork. When a replication fork encounters such a barrier, it can undergo a process termed fork collapse in which its replisome partially or completely dissociates from the DNA. To help ensure the successful completion of DNA replication during the cell cycle, eukaryotic cells use two alternative enzymatic pathways to repair and restart replication forks that collapse following collision with a barrier. The goal of this project is to understand how these restart pathways work, focusing on the least understood of the two, which has been implicated in promoting cancer cell survival. We will identify the components of the pathway and study how they function. To achieve these objectives, we will exploit the genetic tractability of a simple model eukaryote. However, the fundamental aspects of biology that will be studied are highly conserved and, therefore, our discoveries will provide a valuable paradigm to guide future research in human cells. Ultimately, our work will contribute to a greater understanding of replication restart - knowledge that will be vital for guiding the development of novel cancer therapies.