E2F7 & E2F8 in the control of transcription and cellular proliferation

描述（由申请人提供）：转录因子的E2 F家族被认为在控制细胞增殖中起关键作用。这些因子由不同的基因编码，具有肿瘤抑制和致癌功能（1-2）。我们的实验室鉴定E2 F7和E2 F8为该转录因子家族的最后两个成员（5，6）。本提案中提出的初步数据突出了这两种E2 F的几个独特特征，这些特征将它们置于自己的子类中。这些显著特征包括它们形成同源二聚体和异源二聚体的能力，与大量转录辅阻遏物相关联的能力，沉默基因表达的能力，以及阻断细胞增殖的能力。虽然它们缺乏典型的Rb结合结构域，但E2 F7可以特异性地与Rb相关蛋白相互作用，从而可以将E2 F8募集到含Rb的复合物中。因此，E2 F网络的E2 F7/8臂仍然处于循环依赖性激酶（CDK）信号传导途径的控制下。E2 F7和E2 F8具有相同的细胞周期依赖性和组织特异性表达模式，以及它们同源和异源二聚化的能力，这一事实提出了它们在动物中可能具有独特和共享功能的可能性。实验室的多方面努力取得了关键的技术发展，包括纯化E2 F7/8相关蛋白的亲和纯化策略，识别靶基因的启动子阵列技术，以及破坏小鼠E2 F7和E2 F8的基因靶向方法。这些进展使我们的研究小组处于有利地位，可以对E2 F家族因子的这一重要分支如何控制细胞周期和细胞增殖的机制理解取得重大进展。该提议的首要假设是E2 F7和E2 F8作为转录抑制因子起负控制细胞增殖的作用。利用生物化学、生物物理、全球基因阵列和遗传方法的三个具体目标将直接检验这一假设：具体目标1。鉴定和表征E2 F7和E2 F8相关大分子蛋白复合物。具体目标2。鉴定E2 F7和E2 F8转录靶点。具体目标3。确定E2 F7和E2 F8在转录调控中的作用机制。这项工作将阐明这两个高度相关的家庭成员对E2 F转录活性的整体理解的个人和组合的贡献。

DESCRIPTION (provided by applicant): The E2F family of transcription factors is believed to play a critical role in the control of cellular proliferation. These factors are encoded by distinct genes and have both tumor suppressor and oncogenic functions (1-2). Our laboratory identified E2F7 and E2F8 as the final two members of this transcription factor family (5, 6). The preliminary data presented in this proposal highlight several unique features of these two E2Fs that place them in a subclass of their own. These salient features include their ability to form homodimers and heterodimers, to associate with a large cadre of transcriptional co-repressors, to silence gene expression, and to block cellular proliferation. While they lack a typical Rb-binding domain, E2F7 can specifically interact with Rb related proteins and can thus recruit E2F8 to Rb-containing complexes. As a result, the E2F7/8 arm of the E2F network remains under the control of the cycling dependent kinase (CDK) signaling pathway. The fact that E2F7 and E2F8 have an identical pattern of cell cycle dependent and tissue- specific expression, together with their ability to homo- and hetero-dimerize, raises the possibility that they may have both unique and shared functions in the animal. A multi-faceted effort in the laboratory has yielded key technical developments, including an affinity purification strategy to purify E2F7/8-associated proteins, promoter-array technologies to identify target genes, and gene targeting approaches to disrupt E2F7 and E2F8 in mice. These advances place our research group in a strong position to make significant advances towards a mechanistic understanding of how this important arm of the E2F family of factors controls the cell cycle and cell proliferation. The overarching hypothesis of this proposal is that E2F7 and E2F8 function as transcriptional repressors to negatively control cellular proliferation. Three specific aims utilizing biochemical, biophysical, global gene array, and genetic approaches will directly test this hypothesis: Specific Aim 1. To identify and characterize E2F7- and E2F8-associated macromolecular protein complexes. Specific Aim 2. To identify E2F7 and E2F8 transcriptional targets. Specific Aim 3. To determine the mechanism of E2F7 and E2F8 action in the control of transcription. This work will elucidate the individual and combinatorial contributions made by these two highly related family members towards the overall understanding of E2F transcriptional activity.