Mapping the indirect p53 gene regulatory network

转录因子P53是肿瘤进展的中心抑制因子。它通过调节过多的靶基因来控制细胞的增殖和凋亡。然而，目前还不清楚p53是如何调控其许多靶基因的，除了p53本身之外，还有哪些因素是上调或下调调控所必需的，以及它们的调控对正常细胞或癌细胞有什么作用。我们对P53依赖的基因调控的分子基础的不完整图景仍然是我们对肿瘤抑制的整体理解的关键差距。我认为，在P53基因调控网络中的几个通路对响应P53激活的独立的、不同的和必要的基因调节活动起作用。为了确定调节p53依赖的基因调控的新因素，我将采用我之前开发的一种新的荟萃分析方法。基于这种方法，我确定了一个潜在的p53-p21依赖的转换，从MYC-MAX到MAD-MAX启动子占位。为了剖析转录因子介导P53依赖的基因调控的分子机制，我们将使用生化和遗传学方法。该方案的目的是区分介导p53依赖的转录调控的特定调控因子的作用，并确定它们在肿瘤抑制中的作用。目的1：为了确定候选转录因子，如MYC/MAD/Max，对p53依赖的基因调控的影响，我们将采用双重方法。我们将通过荟萃分析确定高置信度的靶基因，并进行实验以确定差异转录因子结合的影响、对特定启动子元件的要求以及细胞反应的变化。目标2：为了系统地确定其他候选基因，我将使用我的荟萃分析方法，测试哪些因子丰富了与P53调控基因结合的独立于DREAM和P53结合的因素。此外，鉴于小鼠模型在弥合基础研究和临床研究之间的差距方面的重要作用，我将确定人类和小鼠之间介导间接p53依赖基因调控的候选途径的保守性。我将确定高置信度的目标基因图谱，并确定人类和老鼠基因列表之间的重叠和差异。综上所述，这些结果将使我们更好地理解多个途径如何协同工作来介导P53依赖的基因调控。这一应用试图挑战和改变目前形成我们理解P53信号通路在生长抑制中的基础的范式。将开发依赖于p53的转录调控的详细分子图谱，并将确定干扰间接调控的后果。实现这项提案的目标将澄清哪些因素介导了P53依赖的基因调控，以及它们如何对肿瘤抑制做出贡献。了解p53是如何抑制肿瘤进展的可能会发现控制细胞生长的新的治疗靶点。

The transcription factor p53 serves as a central suppressor of tumor progression. It controls cell proliferation and apoptosis by regulating a plethora of target genes. However, it is not clear how p53 regulates many of its target genes, what factors besides p53 itself are necessary for up or downregulation and what their regulation contributes to a normal or cancer cell. Our incomplete picture of the molecular basis of p53-dependent gene regulation remains a critical gap to our overall understanding of tumor suppression.I propose that several pathways in the p53 gene regulatory network contribute independent, distinct and essential gene regulatory activities in response to p53 activation. To identify novel factors that mediate p53-dependent gene regulation, I will employ a novel meta-analysis approach that I developed earlier. Based on this approach, I identified a potential p53-p21-dependent switch from MYC-MAX to MAD-MAX promoter occupancy. To dissect the molecular mechanisms by which the transcription factors mediate p53-dependent gene regulation, we will use biochemical and genetic approaches. The goals of this proposal are to distinguish contributions of specific regulators that mediate p53-dependent transcriptional regulation and to determine their roles in tumor suppression.Aim 1: To determine the impact of candidate transcription factors, such as MYC/MAD/MAX, on p53-dependent gene regulation, we will employ a dual approach. We will identify high confidence target genes with the meta-analysis and perform experiments to determine the impact of differential transcription factor binding, the requirement for specific promoter elements and changes in cellular response.Aim 2: To systematically identify additional candidates, I will employ my meta-analysis approach and test what factors are enriched for binding p53 regulated genes independent of DREAM and p53 binding. Moreover, given the important role of mouse models in bridging the gap between basic and clinical research, I will determine conservation of candidate pathways mediating indirect p53-dependent gene regulation between human and mouse. I will identify high confidence target gene maps and determine overlaps and differences between the human and mouse gene lists. Together, the results will provide a better understanding on how multiple pathways work in concert to mediate p53-dependent gene regulation.This application seeks to challenge and shift current paradigms that form the basis of our understanding of p53 signaling pathways in growth suppression. A detailed molecular profile of p53-dependent transcriptional regulation will be developed and the consequences of perturbing indirect regulators will be determined. Achieving the goals of this proposal will clarify what factors mediate p53-dependent gene regulation and how they contribute to tumor suppression. Understanding how p53 suppresses tumor progression may identify novel therapeutic targets to control cell growth.