Differential Regulation of p53 function by Lysine Acetylation

描述(申请人提供)：应激诱导的P53的C-末端赖氨酸乙酰化在P53作为一种转录因子的活性中起着重要的作用，该转录因子调节细胞周期停滞、衰老或凋亡。该项目的长期目标是寻求对调节肿瘤抑制基因P53的分子相互作用的机械性理解。虽然已经报道了其C末端的多个乙酰化位点，但这些赖氨酸残基单独或联合乙酰化对P53活性的具体影响仍然难以捉摸。初步的数据涉及对P53功能的分析，即乙酰化诱导的P53激活响应于DMA损伤参与了共激活因子的募集。这项研究揭示了P53的募集需要CBP(CREB结合蛋白)的保守溴结构域与P53在乙酰化Iys382处的结合：这是一种特定的分子相互作用，对于P53诱导的细胞周期蛋白依赖的激酶抑制物p21的转录激活是必不可少的，该抑制物参与了G1细胞周期的停滞。我们假设，在不同的条件下，P53 C末端残基的不同修饰，包括赖氨酸乙酰化和泛素化，以及丝氨酸磷酸化，对细胞中的P53功能有不同的影响。提出了一种多方面的方法来解决P53转录激活的机制基础，重点是C末端翻译后修饰在P53激活中的作用。为了了解P53调控的复杂分子机制，我建议研究P53的乙酰化动力学和涉及其C端赖氨酸的分子相互作用。为了实现这一目标，人们提出了三个具体的目标：(1)研究正常和肿瘤细胞系中P53功能的C-末端赖氨酸的乙酰化动力学；(2)利用ChIP和siRNAs阐明共激活因子p300和CBP在P53调控中的不同作用；以及(3)使用新开发的CBP溴结构域结合小分子抑制剂在细胞生长停滞和凋亡之间调节P53的活性。这些拟议研究的新结果有望加强我们对P53功能中C末端修饰的分子基础的理解。鉴于P53在癌症中的核心作用，这些研究将对人类肿瘤的预后和治疗具有重要意义。

DESCRIPTION (provided by applicant): Stress-induced C-terminal lysine acetylation of p53 plays an important role in the activity of p53 as a transcription factor that regulates cell cycle arrest, senescence or apoptosis. The long-term goal of this Project is to seek mechanistic understanding of the molecular interactions that regulate the tumor suppressor p53. While multiple acetylation sites in its C-terminal tail have been reported, specific effects of individual or combined acetylation of these lysine residues on p53 activity remain elusive. Preliminary data is presented involving the analysis of p53 function that acetylation-induced p53 activation in response to DMA damage is involved in co-activator recruitment. This study revealed that p53 recruitment of the co-activator CBP (CREB binding protein) requires association of the conserved bromodomain of CBP with p53 at acetylated Iys382: a specific molecular interaction that is essential for p53-induced transcriptional activation of the cyclin- dependent kinase inhibitor p21, involved in G1 cell cycle arrest. We hypothesize that distinct modifications of p53 C-terminal residues, including lysine acetylation and ubiquitination, as well as serine phosphorylation, have differential effects on p53 functions in cells under different conditions. A multifaceted approach is proposed to address mechanistic underpinnings of p53 transcriptional activation with the emphasis on the role of C-terminal post-translational modifications in p53 activation. To understand the complex molecular mechanisms underlying p53 regulation, I propose to investigate the dynamics of acetylation and molecular interactions of p53 involving its C-terminal lysines. Three specific aims are proposed to achieve this goal: (1) to investigate the kinetics of acetylation of the C-terminal lysines in p53 function in normal and tumor cell lines; (2) to elucidate the differential roles of the co-activators p300 and CBP in p53 regulation using CHIP and siRNAs; and (3) to modulate p53 activity between cell growth arrest and apoptosis using the newly developed CBP Bromodomain-binding small molecule inhibitors. The emerging results from the proposed studies are expected to enhance our understanding of the molecular basis of C-terminal modifications in p53 function. Given the central role of p53 in cancer, these studies will have important implications for the prognosis and treatment of human tumors.