The ATM/E2F1 Pathway in DNA Damage and Growth Control

描述（由申请人提供）：转录因子E2 F1在控制细胞增殖和凋亡中起关键作用。最近，我们发现了一个新的口袋蛋白独立的途径，涉及PI 3 K/Akt和一个BRCT结构域的蛋白TopBP 1在控制E2 F 1我们的初步数据进一步证明E2 F可以调节另一个BRCT结构域的蛋白，MCPH 1/BRIT 1。pRb家族成员长期以来被认为是E2 F的主要调节剂。TopBP 1和MCPH 1似乎是一类新的E2 F调节剂。它们都含有多个BRCT基序，并通过它们的BRCT基序与E2 F1的N-末端相互作用。TopBP 1是E2 F1靶基因在检查点/修复和凋亡中的负调控因子，而MCPH 1是E2 F1靶基因在检查点/修复和凋亡中的正调控因子。这两种蛋白质也直接参与DNA损伤检查点激活。在这项提案中，我们的目标是表征这些新的调节E2 F1蛋白的活性和稳定性的功能和机制。首先，我们将阐明生长因子信号通过TopBP 1控制E2 F1的机制。其次，我们将确定MCPH 1如何调节E2 F1。TopBP 1和MCPH 1如何响应环境并调节E2 F1活性也将被研究。最后，我们将研究E2 F1蛋白是如何诱导ATM磷酸化的。在完成这个项目后，我们将阐明E2 F1的增殖和促凋亡活性是如何差异调节的。了解E2 F1活性的控制以及在生长和DNA损伤中的稳定性可能提供利用E2 F1促凋亡活性以增强化学敏感性的新方法。公共卫生相关性：增殖和细胞死亡之间的适当平衡对正常生长至关重要。最近的研究已经确定了E2 F1在这种控制中的作用，特别是在DNA损伤时。在上一次资助期间，我们发现了一类新型的E2 F1调节器。我们将阐明调节机制和在癌症治疗中增强E2 F1诱导的细胞杀伤的临床应用的意义。

DESCRIPTION (provided by applicant): The transcription factor E2F1 plays a pivotal role in the control of cell proliferation and apoptosis. Recently we uncovered a novel pocket proteins-independent pathway involving PI3K/Akt and a BRCT domain-containing protein TopBP1 in the control of E2F1 Our preliminary data further demonstrate E2F can be regulated by another BRCT domain-containing protein, MCPH1/BRIT1. The pRb family members have long been considered to be the major regulators for E2F. TopBP1 and MCPH1 appear to be a new class of E2F regulators. They both contain multiple BRCT motifs and interact with the N- terminus of E2F1 through their BRCT motifs. TopBP1 is a negative regulator, whereas, MCPH1 is a positive regulator of E2F1 target genes in checkpoint/repair and apoptosis. Both proteins are also directly involved in DNA damage checkpoint activation. In this proposal, we aim to characterize the functions and mechanisms of these novel regulations governing E2F1 protein activity and stability. First, We will elucidate the mechanism by which growth factor signalings control E2F1 through TopBP1. Second, We will determine how MCPH1 regulates E2F1. How TopBP1 and MCPH1 respond to environmental milieu and regulate E2F1 activity will also be investigated. Lastly, we will investigate how E2F1 protein is induced in response to ATM phosphorylation. Upon completion of this project, we will elucidate how the proliferative and pro-apoptotic activities of E2F1 are differentially regulated. Understanding the control of E2F1 activity and stability in growth and DNA damage may provide novel approaches in harness E2F1 pro-apoptotic activity to enhance chemosensitivity. PUBLIC HEALTH RELEVANCE: Proper balance between proliferation and cell death is essential for normal growth. Recent studies have established a role for E2F1 in this control, especially upon DNA damage. During our last grant period, we discovered a novel class of E2F1 regulators. We will elucidate the mechanisms of regulation and the implications to clinical application in enhancing E2F1-induced cell killing in cancer therapy.