Structural basis for CBP/p300 transcriptional regulation

描述（由申请人提供）：CREB结合蛋白（CBP）和p300是真核细胞中整合多种信号转导途径的通用转录调节因子，作为基因表达的共激活因子和抑制因子。它们对细胞的生长、分化、凋亡和胚胎发育等基本功能至关重要。它们还可以作为肿瘤抑制因子并调节控制细胞增殖、肿瘤发生和癌症进展的关键基因。由于CBP和p300在关键细胞信号网络中的作用，它们是许多细胞和病毒癌蛋白的靶标。本研究的目的是阐明CBP和p300发挥其中心调控作用以防止或促进致癌转化的结构和分子基础。该研究将重点阐明CBP和p300与肿瘤抑制因子p53和人乳头瘤病毒转化癌蛋白相互作用的分子决定因素。p53被一个复杂的磷酸化级联激活，导致p53转录激活域和CBP/p300之间的相互作用增强。来自高危人乳头瘤病毒的E6和E7癌蛋白识别并结合CBP/p300，抑制p53介导的转录途径，防止细胞凋亡，转化宿主细胞。最先进的结构、生物物理和蛋白质组学工具将用于阐明关键的CBP/p300相互作用的分子基础，这些相互作用负责激活p53对DNA损伤的反应，高危人乳头瘤病毒株对宿主细胞的永生化和转化，以及损伤反应基因的调节和抑制。这项研究将为以下方面提供新的见解：p53调控基因在基因毒性应激下的激活机制，高危人乳头瘤病毒癌蛋白破坏细胞调控机制以实现细胞永生和转化的分子相互作用，以及CBP作为转录抑制因子的功能。

DESCRIPTION (provided by applicant): CREB binding protein (CBP) and p300 are general transcriptional regulators that integrate numerous signal transduction pathways in eukaryotic cells, functioning both as coactivators and repressors of gene expression. They are essential for such basic cellular functions as growth, differentiation, apoptosis, and embryonic development. They also function as tumor suppressors and regulate key genes that control cellular proliferation, tumorigenesis, and cancer progression. Because of their function at the nexus of critical cell signaling networks, CBP and p300 are targeted by many cellular and viral oncoproteins. The goals of the present proposal are to elucidate the structural and molecular basis by which CBP and p300 perform their central regulatory roles to protect against or promote oncogenic transformation. The research will focus on elucidation of the molecular determinants by which CBP and p300 interact with the tumor suppressor p53 and with transforming oncoproteins from human papillomavirus. p53 is activated by a complex phosphorylation cascade that results in enhanced interactions between the p53 transcriptional activation domain and CBP/p300. The E6 and E7 oncoproteins from high risk human papillomavirus recognize and bind CBP/p300 to repress p53-mediated transcriptional pathways, prevent apoptosis, and transform the host cell. State-of-the-art structural, biophysical, and proteomics tools will be utilized to elucidate the molecular basis for key CBP/p300 interactions responsible for activation of the p53 response to DNA damage, immortalization and transformation of the host cell by high risk human papillomavirus strains, and regulation and repression of damage response genes. This research will provide novel insights into the mechanism of activation of p53-regulated genes in response to genotoxic stress, into the molecular interactions through which high risk human papillomavirus oncoproteins subvert the cellular regulatory machinery to immortalize and transform the cell, and into the function of CBP as a transcriptional repressor.