Transcriptional regulation by the DNA damage response

 描述(由申请人提供)：保持基因组的完整性对于防止容易导致发育障碍和癌症的突变和基因组重排的积累至关重要。双链断裂(DSB)是由电离辐射等DNA损伤剂引起的或在DNA复制和转录过程中自发形成的潜在致命DNA损伤。在DSB形成后，DNA损伤反应(DDR)的激活促进了基因组的完整性。ATM激酶是DDR的主要组成部分，它通过调节从DNA修复和复制到剪接和转录的大量细胞活动来维持基因组对DSB的稳定。ATM与奈梅根断裂综合征蛋白NBS1协同作用，抑制电离辐射后核糖体DNA(RDNA)的转录。我们最近发现，在对电离辐射的反应中，NBS1定位于核仁，在那里它与Treacher Collins综合征蛋白TCOF1结合，以抑制rDNA转录。尽管有这些重要的观察，但目前还缺乏对电离辐射后rDNA转录调控机制的完全了解。这项建议的目的是阐明ATM是如何与NBS1和TCOF1在电离辐射后抑制rDNA转录的，并研究rDNA转录的缺陷抑制如何导致基因组不稳定。特别是，我们建议：1)阐明ATM和CK2调节电离辐射后NBS1和TCOF1之间相互作用的机制；2)确定ATM、NBS1和TCOF1抑制核糖体DNA转录响应电离辐射的过程；3)确定ATM-NBS1-TCOF1途径维持基因组稳定性的机制。我们的方法将结合分子和细胞生物学技术与蛋白质组和生化分析，提供详细的了解导致和导致电离辐射后ATM、NBS1和TCOF1介导的rDNA转录抑制的分子事件。我们预计，我们的研究将阐明ATM和NBS1确保基因组对电离辐射响应的稳定性的新过程。

 DESCRIPTION (provided by applicant): Maintenance of genomic integrity is essential to prevent the accumulation of mutations and genomic rearrangements that predispose to developmental disorders and cancer. Double-strand breaks (DSBs) are potentially lethal DNA lesions induced by DNA damaging agents, such as ionizing radiation, or spontaneously formed during DNA replication and transcription. Following DSB formation, activation of the DNA damage response (DDR) promotes genomic integrity. The ATM kinase is a principal DDR component that maintains genomic stability in response to DSBs by regulating a large number of cellular activities, ranging from DNA repair and replication to splicing and transcription. ATM cooperates with the Nijmegen breakage syndrome protein NBS1 to suppress ribosomal DNA (rDNA) transcription after ionizing radiation. We have recently shown that in response to ionizing radiation NBS1 localizes to nucleoli, where it associates with the Treacher Collins syndrome protein TCOF1 to suppress rDNA transcription. Despite these important observations, a complete understanding of the mechanisms by which rDNA transcription is regulated after ionizing radiation is currently lacking. The goal of this proposal is to elucidate how ATM cooperates with NBS1 and TCOF1 to suppress rDNA transcription after ionizing radiation and examine how defective inhibition of rDNA transcription causes genomic instability. In particular, we propose: 1) to elucidate the mechanisms by which ATM and CK2 regulate the interaction between NBS1 and TCOF1 after ionizing radiation; 2) to determine the processes through which ATM, NBS1 and TCOF1 suppress ribosomal DNA transcription in response to ionizing radiation; 3) to define the mechanisms by which the ATM-NBS1-TCOF1 pathway maintains genomic stability. Our approach will combine molecular and cell biology techniques with proteomic and biochemical assays to provide a detailed understanding of the molecular events that lead to and result from the inhibition of rDNA transcription mediated by ATM, NBS1 and TCOF1 after ionizing radiation. We anticipate that our studies will elucidate novel processes through which ATM and NBS1 ensure the stability of the genome in response to ionizing radiation.