E2F AND THE CONTROL OF CELLULAR PROLIFERATION

肿瘤抑制蛋白pRb通过以下方式控制细胞周期的重新进入 调节被称为E2F的转录因子家族的活性。 这项提案的重点是调查 将E2F家庭成员之间的反馈调节与 其上游调控因子pRb和两个pRb相关蛋白的作用， 称为P107和P130。最终理解这些问题应该会导致 为了理解这条通路的上游调控信号是如何 转化为一种精确调控的下游模式 转录激活控制细胞增殖。到目前为止，有7个 已经确定了编码E2F组分的基因。产品 这些基因可以细分为两个不同的类别，称为E2F (1至5)和DP(1和2)，其产物异二聚得到 上升到功能性E2F活动。内源性的复杂属性 E2F活性源于不同的性质，因此具有生物学意义 多个E2F/DP异源二聚体的活性。要准确地评估 这些E2F的生化和功能活性，特异性 已经针对每一种成分开发出了单抗 E2F系统。使用这些特定的抗体，耐人寻味 关于细胞周期调控的意外观察 合成了内源E2F/DP络合物。尤其是E2F-4 在细胞周期中经历其亚细胞定位的变化 一种依赖的方式，似乎在调解 PRb、p107和p130的不同生物学特性。这些研究 提示E2F-4可能在调节细胞活性中发挥关键作用。 整个E2F家族，因此充当内源性 E2F活性及pRb、p107和p130活性。出于这些原因，这 提案的重点是了解E2F-4的本地化 有助于调节内源性E2F活性。这个 具体目标如下：描述细胞周期 内源性E2F复合体的依赖定位，阐明 E2F差异定位的机制 络合物是介导性的，并分析了其生物学功能 E2F复合体。

The tumor suppressor protein, pRB, controls cell cycle re-entry by regulating the activity of a family of transcription factors called E2F. The focus of this proposal is to investigate the processes which integrate feedback regulation among the E2F family members with the action of their upstream regulators, pRB and two pRB-related proteins, called p107 and p130. Ultimately understanding these issues should lead to an understanding of how upstream regulatory signals from this pathway are converted into a precisely regulated pattern of downstream transcriptional activation controlling cell proliferation. To date, seven genes have been identified that encode components of E2F. The products of these genes can be subdivided into two distinct classes, called E2F (1 through 5) and DP (1 and 2), whose products heterodimerize to give rise to functional E2F activity. The complex properties of the endogenous E2F activity arises from the varied properties and hence biological activities of the multiple E2F/DP heterodimers. To accurately assess these biochemical and functional activities of the E2Fs, specific monoclonal antibodies have been developed for each of the components of the E2F system. Using these specific antibodies, intriguing and unexpected observations regarding the cell cycle regulation of the endogenous E2F/DP complexes have been made. In particular, E2F-4 undergoes changes in its subcellular localization in a cell cycle dependent manner which appears to play a pivotal role in mediating the different biological properties of pRB, p107 and p130. These studies suggest that E2F-4 may play a key role in regulating the activity of the entire E2F family and hence acts as master regulator of the endogenous E2F activity and of pRB, p107 and p130 action. For these reasons, this proposal is focused on understanding how the localization of E2F-4 contributes to the regulation of the endogenous E2F activity. The specific aims are as follows: characterization of the cell cycle dependent localization of the endogenous E2F complexes, elucidation of the mechanisms by which the differential localization of the E2F complexes is mediated, and analysis of the biological functions of the E2F complexes.