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： 调节称为E2 F的转录因子家族的活性。 本提案的重点是调查 整合E2 F家族成员之间的反馈调节， 其上游调节因子pRB和两种pRB相关蛋白的作用， P107和P130。最终了解这些问题应该会导致 来理解这个通路的上游调控信号 转化成一种精确调节的下游模式， 转录激活控制细胞增殖。迄今为止， 已经鉴定了编码E2 F组分的基因。产品 这些基因可以分为两个不同的类，称为E2 F （1至5）和DP（1和2），其产物异二聚化得到 增强E2 F的活性。内生性的复杂性质 E2 F活性由不同的性质引起，因此是生物学上的。 多个E2 F/DP异二聚体的活性。准确评估 E2 Fs的这些生化和功能活性， 已经开发了用于每种组分的单克隆抗体， E2 F系统。利用这些特异性抗体， 关于细胞周期调节的意想不到的观察结果， 已经制备了内源性E2 F/DP复合物。特别是，E2 F-4 在细胞周期中其亚细胞定位发生变化 依赖的方式，似乎发挥了关键作用，在调解 pRB、p107和p130的不同生物学特性。这些研究 提示E2 F-4可能在调节E2 F-4的活性中起关键作用。 整个E2 F家族，因此作为内源性的主要调节因子， E2 F活性和pRB、p107和p130作用。由于这些原因，这 该提案的重点是了解E2 F-4的本地化 有助于调节内源性E2 F活性。的 具体目标如下：细胞周期的表征 内源性E2 F复合物的依赖性定位， E2 F差异定位的机制 复合物是介导的，并分析的生物功能， E2 F复合物。

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.