Repair of DNA breaks in human: the role of Rad54 protein

描述（由申请人提供）：电离辐射（IR）和交联剂（CLA）诱导DNA双链断裂（DSB）。DSB是最有害的DNA损伤类型，其导致基因组不稳定，导致癌症、遗传疾病和人类过早衰老。然而，IR和CLA与顺铂一样，也常用于肿瘤治疗。因此，研究DSB修复的机制至关重要。最近的研究表明，同源重组（HR）的细胞系统在所有物种的DSB修复中起着至关重要的作用。为了确保DNA修复的准确性，HR系统使用同源dsDNA作为模板。Rad51蛋白在所有生物体中寻找同源DNA序列和DNA配对中起着关键作用。在真核生物中，Rad51蛋白通过与其他HR蛋白形成瞬时复合物来刺激其DNA配对活性来执行其功能。在这些刺激蛋白中，Rad54蛋白尤为重要。该提案的长期目标是有助于了解DSB修复中人类HR蛋白复合物的功能。一般的方法是表征纯化的人HR蛋白的特定功能，并在体外研究它们的相互作用。目前，我们主要研究人Rad54蛋白在DNA修复中的功能。我们将努力实现以下具体目标。1）。我们将研究Rad54蛋白的生化特性，并确定Rad54蛋白与DNA结合的机制。2）。我们将研究在DSB修复中最重要的两个蛋白Rad54和Rad51之间的相互作用，并确定Rad54蛋白如何增强Rad51蛋白修复DSB的能力的机制。反过来，我们研究如何与Rad51蛋白的相互作用影响Rad54蛋白的性质。3）。我们将研究Rad54蛋白与Rad51C蛋白的相互作用，Rad51C蛋白是另一种HR蛋白，具有DNA配对活性，尽管很弱。4）。我们将研究与人类肿瘤相关的Rad54蛋白突变体的生物化学活性。从所有这些研究中，将阐明人Rad54蛋白在DSB修复中的作用。本研究获得的知识将有助于更好地理解HR的基本机制，并将用于开发有效的肿瘤治疗方法。

DESCRIPTION (provided by applicant): Ionizing radiation (IR) and cross-linking agents (CLA) induce DNA double-stranded breaks (DSB). DSB are the most harmful type of DNA damage, which causes genome instability leading to cancer, genetic diseases, and premature aging in human. However, IR and CLA, like cis-platin, are also commonly used in tumor therapy. Therefore, investigation of the mechanisms of DSB repair is crucially important. Recent discoveries have demonstrated that the cellular system of homologous recombination (HR) plays an essential role in DSB repair in all species. To insure the accuracy of DNA repair, the HR system uses homologous dsDNA as a template. Rad51 protein plays a key role in the search for homologous DNA sequences and for DNA pairing in all organisms. In eukaryotes, Rad51 protein carries out its function by forming transient complexes with other HR proteins that stimulate its DNA pairing activity. Among the stimulatory proteins, Rad54 protein is especially important. The long-term goal of this proposal is to contribute to understanding of the functions of the human HR protein complexes in DSB repair. The general approach is to characterize the specific functions of purified human HR proteins and investigate their interactions in vitro. Currently, we focus our investigation on the functions of human Rad54 protein in DNA repair. We will pursue the following specific aims. 1). We will study the biochemical properties of Rad54 protein and determine the mechanism of Rad54 protein binding to DNA. 2). We will investigate the interaction between Rad54 and Rad51, two most important proteins in DSB repair, and determine the mechanism how Rad54 protein enhances the ability of Rad51 protein to repair DSB. Reciprocally, we examine how interactions with Rad51 protein affect the properties of Rad54 protein. 3). We will examine the interaction of Rad54 protein with Rad51C protein, another HR protein, which has DNA pairing activity, albeit weak. 4). We will examine the biochemical activities of Rad54 protein mutants associated with human tumors. From all these studies the role of human Rad54 protein in DSB repair will be elucidated. The knowledge acquired in this study will help to better understand the fundamental mechanisms of HR and will be applied for developing efficient tumor therapies.