Defining the role of PARPs in the DNA repair and genome stability

通过修复受损的DNA来保持遗传物质的完整性对生物体的健康至关重要。解决不同DNA损伤的DNA修复机制正变得越来越明确。然而，剩下的挑战是了解这些过程如何整合，以便在特定修复途径失败时允许细胞存活。破译这些复杂的相互作用将定义基因组稳定性的机制基础，并揭示操纵这些途径以获得临床益处的策略。我的实验室专注于解决这些重要问题，特别是一组称为聚（ADP-核糖）-聚合酶（PARP）的酶如何调节DNA修复。PARP的最佳定义作用是促进DNA双链螺旋断裂的修复。使用小分子PARP抑制剂（PARPi）抑制该途径正在临床上被开发用于杀死在被称为同源重组（HR）的DNA修复过程中具有缺陷的肿瘤。我们目前对这一过程的理解是，PARPi可以在DNA断裂处“捕获”两种酶，PARP 1和PARP 2。这些PARP-DNA加合物然后在DNA复制过程中阻断复制遗传物质的酶，导致DNA损伤，需要HR进行修复。因此，在没有HR的情况下，细胞由于不能修复PARPi诱导的复制阻断而被杀死。重要的是，我们以前的MRC资助的工作表明，这些机制中存在显著的功能重叠，PARP 1/PARP 2不仅促进DNA断裂的修复，还促进复制块的分解。拟议的工作将建立在这些关键的概念性进展，以及来自我实验室的令人兴奋的新数据的基础上，以进一步定义PARP如何促进基因组的完整性。具体来说，我们将研究一种额外的PARP依赖性机制来修复复制障碍，以及一种新的基因，可以补偿PARP 1/PARP 2的丢失。这些研究不仅将增加我们对允许细胞保持基因组完整性的基本原理的理解，而且还将提供关键信息，支持开发更具特异性的PARPi，提高临床疗效。此外，当PARP被破坏时，识别对细胞活力至关重要的基因将确定策略，以扩大这些药物的使用，以治疗HR以外的途径存在缺陷的肿瘤类型。

Preserving the integrity of genetic material through repair of damaged DNA is critical for the health of an organism. DNA repair mechanisms that resolve different DNA lesions are becoming increasingly well defined. However, a remaining challenge is to understand how these processes integrate to allow cell survival if a particular repair pathway fails. Deciphering these complex interactions will define the mechanistic basis of genome stability and uncover strategies to manipulate these pathways for clinical benefit. My laboratory is focussed on addressing these important questions, with specific reference to how a set of enzymes called Poly(ADP-ribose)-polymerases (PARPs) regulate DNA repair.The best defined role of PARPs is in promoting repair of breaks in the DNA double strand helix. Inhibition of this pathway using small molecule PARP inhibitors (PARPi) is being exploited in the clinic to kill tumours with defects in a DNA repair process known as homologous recombination (HR). Our current understanding of this process is that PARPi can 'trap' two enzymes, PARP1 and PARP2 at DNA breaks. These PARP-DNA adducts then blocks enzymes that copy genetic material during DNA replication, causing DNA damage that requires HR for repair. Therefore, in the absence of HR, cells are killed due to their inability to repair PARPi-induced replication blocks. Importantly, our previous MRC funded work indicated that there is significant functional overlap in these mechanisms and that PARP1/PARP2 not only promote repair of DNA breaks, but also resolution of replication blocks. The proposed work will build on these key conceptual advances in addition to exciting new data from my laboratory to further define how PARPs promote genome integrity. Specifically, we will characterise an additional PARP-dependent mechanism to repair replication blocks, in addition to a novel gene that can compensate for loss of PARP1/PARP2.These studies will not only increase our understanding of fundamental principles that allow cells to maintain genome integrity, but also provide critical information that will underpin development more specific PARPi with increased efficacy in the clinic. Moreover, identifying genes that are critical for cell viability when PARPs are disrupted will identify strategies to broaden the use of these agents to treat tumour types with defects in pathways other than HR.