ErbB Receptor Control of Breast Cancer Growth

描述(申请人提供)：我们最近克隆了一种新的蛋白质， Ebp1，它与ErbB-3受体的细胞质结构域相互作用。 ErbB-3配体HERG对细胞的诱导作用 Ebp1从细胞质到细胞核的转位。受管制的核 Ebp1的积累表明它可能作为转录因子发挥作用 在激活前隔离在细胞质中的辅助调节因子，类似于 Stat或Smads。Ebp1过表达抑制细胞增殖和诱导 人乳腺癌细胞的分化。Ebp1与肿瘤相互作用 抑制蛋白、Rb和辅抑制子Sin3A，并抑制转录 与细胞周期相关的基因。目前提案的总体目标是 进一步了解EBP L转录抑制的机制 确定转录抑制能力如何影响Ebp1‘S 生物效应。在具体目标1中，我们将确认Ebp1诱导的作用 调节其生物学效应的转录抑制。特定的 实验包括：1)测定Ebp1调节活性的能力 2)鉴定和定位Ebp1转录 抑制结构域3)描绘Ebp1与以下成分的相互作用 组蛋白脱乙酰酶(HDAC)复合体4)评估Ebp1结合能力 DNA作为蛋白质复合体的一部分检测Ebpl诱导的 转录抑制对其生物学效应的影响6)鉴定Ebp1 有约束力的伙伴。在具体目标2中，我们将继续研究监管 Ebp1通过磷酸化发挥作用。我们将a)确定规则和 不同生长条件下磷酸化Ebp1的亚细胞定位 条件b)使用SELDI技术绘制Ebp1磷酸化位点图并使用 设计磷酸化特异性抗体的知识c)测试Ebp1的能力 磷酸化突变体调节转录，细胞生长，和 差异化。第三，我们将定义正常的生理功能 在哺乳动物系统中通过创造和研究Ebp1基因敲除小鼠。这些 实验应该有助于理解Ebp1是如何 抑制转录有助于其对细胞生长和 差异化。合理和特定的治疗方法的发展 抑制物复合体为癌症治疗提供了新的方向。一个 了解Ebp1抑制细胞生长和诱导细胞生长的机制 分化可能有助于设计新的分子靶点 癌症治疗。

DESCRIPTION (provided by applicant): We have recently cloned a novel protein, Ebp1, which interacts with the cytoplasmic domain of the ErbB-3 receptor. Treatment of cells with the ErbB-3 ligand, heregulin (HRG) induces the translocation of Ebp1 from the cytoplasm to the nucleus. The regulated nuclear accumulation of Ebp1 suggests that it may function as a transcriptional coregulator that is sequestered in the cytoplasm before activation similar to STAT or Smads. Overexpression of Ebp1 inhibits proliferation and induces differentiation of human breast cancer cells. Ebp1 interacts with the tumor suppressor protein, Rb and the corepressor Sin3A, and represses transcription of cell cycle-related genes. The overall aim of the current proposal is to further understand the mechanisms of Ebp l's transcriptional repression and to determine how the ability to repress transcription contributes to Ebp1's biological effects. In Specific Aim 1 we will confirm the role of Ebp1-induced transcriptional repression in mediating its biological effects. Specific experiments include 1) determining the ability of Ebp1 to modulate the activity of endogenous promoters 2) identifying and mapping Ebp1 transcriptional repression domains 3) delineating the interactions of Ebp1 with components of histone deacetylase (HDAC) complexes 4) assessing the ability of Ebp1 to bind DNA as part of a protein complex 5) examining the contribution of Ebpl induced transcriptional repression to its biological effects 6) indentifying Ebp1 binding partners. In specific Aim 2, we will continue to study regulation of Ebp1 function by phosphorylation. We will a) determine the regulation and subcellular localization of phosphorylated Ebp1 under different growth conditions b) map Ebp1 phosphorylation sites using SELDI technology and use this knowledge to design phosphospecific antibodies c) test the ability of Ebp1 phosphorylation mutants to regulate transcription, cell growth, and differentiation. Third, we will define the normal physiological functions of Ebp1 in a mammalian system by the creation and study of knockout mice. These experiments should contribute to an understanding of how the ability of Ebp1 to repress transcription contributes to its effects on cell growth and differentiation. The development of rational and specific therapies that target repressor complexes is providing a new direction in cancer treatment. An understanding of the mechanisms by which Ebp1 inhibits cell growth and induces differentiation may contribute to the design of new molecular targets for cancer therapy.