E2F7 & E2F8 in the control of transcription and cellular proliferation

转录因子的E2 F家族被认为在细胞凋亡的控制中起关键作用。 增殖这些因子由不同的基因编码，具有肿瘤抑制和致癌作用。 函数（1-2）。我们的实验室确定E2 F7和E2 F8是该转录因子的最后两个成员 家庭（5，6）。本提案中提出的初步数据突出了这两个国家的几个独特特征。 E2 F将它们放在自己的子类中。这些显著的特征包括它们能够形成 同源二聚体和异源二聚体，与大量转录辅阻遏物结合，沉默 基因表达，并阻断细胞增殖。虽然它们缺乏典型的Rb结合结构域，但E2 F7可以 E2 F8与Rb相关蛋白特异性相互作用，因此可以将E2 F8募集到含Rb的复合物中。作为 结果，E2 F网络的E2 F7/8臂仍然处于循环依赖性激酶（CDK）的控制下。 信号通路事实上，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，以及它们同源和异源二聚化的能力，提高了它们 可能在动物身上既有独特的功能又有共同的功能。在实验室的多方面努力已经产生了 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， 启动子阵列技术来鉴定靶基因，以及基因靶向方法来破坏E2 F7和 小鼠中的E2 F8。这些进步使我们的研究小组处于有利地位，可以取得重大进展 对E2 F家族的这一重要因子如何控制细胞的机制的理解 周期和细胞增殖。该提议的首要假设是E2 F7和E2 F8的功能是 转录抑制因子负控制细胞增殖。三个具体目标利用生化， 生物物理学、全球基因阵列和遗传学方法将直接检验这一假设：具体目标1。到 鉴定和表征E2 F7-和E2 F8-相关大分子蛋白质复合物。具体目标2。 鉴定E2 F7和E2 F8转录靶点。具体目标3。为了确定E2 F7的作用机制， E2 F8在转录控制中的作用。这项工作将阐明个人和组合 这两个高度相关的家庭成员对E2 F的整体理解所做的贡献 转录活性 项目描述第6页

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 elucida the individual and combinatorial contributions made by these two highly related family members towards the overall understanding of E2F transcriptional activity. Project Description Page 6