Mechanisms for Selective Transcription of p53 Targets by the AcK120 Isoform

AcK120 同工型选择性转录 p53 靶标的机制

基本信息

批准号：
8457388
负责人：
Jessica Monteith
金额：
$ 4.22万
依托单位：
THOMAS JEFFERSON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-03-09 至 2017-03-08
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8457388
关键词：
Acetylation Acetyltransferase Affinity Apoptosis Apoptotic Arginine Binding Biological Cancer Biology Cause of Death Cell Cycle Arrest Cell Death Cells Cessation of life DNA Binding DNA Binding Domain DNA Damage Data Set Enzymes Event Family G1 Arrest Gene Targeting Genes Genetic Genetic Transcription Goals HTATIP gene Half-Life Human Laboratories Lesion Malignant Neoplasms Mediating Methodology Methylation Modeling Modification Mutation Normal Cell Pathway interactions Phosphorylation Play Post-Translational Protein Processing Protein Family Protein Isoforms Protein p53 Proteins Reporting Role Site TP53 gene Testing Therapeutic Therapeutic Intervention Tumor Suppression Tumor Suppressor Proteins base cancer cell cancer initiation cancer therapy carcinogenesis clinically significant cofactor experience genome-wide inhibitor/antagonist multicatalytic endopeptidase complex novel public health relevance response tool tumor tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): The p53 tumor suppressor pathway is inactivated in most forms of human cancer. In normal cells, p53 is maintained at low levels by ubiquitylation and subsequent proteosome-mediated degradation. In addition to ubiquitylation, p53 is regulated by other forms of post-translational modification, including phosphorylation, acetylation and methylation. These modifications regulate a variety of p53 functions, including protein half-life, DNA binding capacity and cofactor interaction. The elimination of p53 function i critical during human carcinogenesis because the normal role of p53 is to induce either cell cycle arrest or apoptosis when a cell sustains genetic damage. As the central regulator of apoptotic cell death, the p53 pathway is of critical importance for chemotherapeutic strategies that induce genotoxic damage. Understanding the key events in the p53/apoptosis pathway is therefore of broad clinical significance. We have demonstrated that p53 is acetylated at a unique site, K120, within the DNA binding domain, by the MYST family enzymes hMOF and TIP60. Acetylation at K120 occurs rapidly after DNA damage and several lines of evidence show this is essential for p53-dependent apoptosis. Further, our empirical studies show that the acetyl-K120 isoform of p53 is enriched at pro-apoptotic target genes, but not cell cycle arrest targets. In addition, conservative mutation of the acetylation site to arginine (K120R) inhibits apoptosis, without blocking G1 arrest. Remarkably, the inactivation of p53 by K120R mutation has been reported in a small number of human tumors, and both the enzymes that catalyze K120 acetylation (i.e. hMOF and TIP60) are lost in human tumors as well. These observations suggest that the activation of the K120-acetylation pathway may be an important tumor suppressor mechanism. Our current model suggests that MYST family proteins acetylate p53 at K120 after DNA damage and that acetylation then selectively enhances transcription of pro-apoptotic target genes by p53. Using recently developed tools and methodologies, we have generated genome-wide data sets that will allow us to identify all loci bound and regulated by the Ac-K120 isoform of p53. The studies proposed here will provide a thorough understanding of the role played by the K120 acetylation pathway in p53 function. Our ultimate goal is to gain sufficient understanding that we will be able to manipulate this pathway in a predictable manner in order to selectively trigger apoptosis in human cancer cells.

描述（由申请人提供）：p53肿瘤抑制途径在大多数形式的人类癌症中被灭活。在正常细胞中，通过泛素化和随后的蛋白体介导的降解，p53保持低水平。除了泛素化外，p53还受其他形式的翻译后修饰调节，包括磷酸化，乙酰化和甲基化。这些修饰调节了各种p53功能，包括蛋白质半衰期，DNA结合能力和辅因子相互作用。消除p53功能I在人类致癌过程中至关重要，因为p53的正常作用是当细胞遭受遗传损害时诱导细胞周期停滞或凋亡。作为凋亡细胞死亡的中心调节剂，p53途径对于诱导遗传毒性损伤的化学治疗策略至关重要。因此，了解p53/凋亡途径中的关键事件具有广泛的临床意义。我们已经证明，Myst家族酶HMOF和TIP60在DNA结合结构域内的独特位点K120中对p53进行了乙酰化。 K120时的乙酰化发生在DNA损伤后迅速发生，几条证据表明，这对于依赖p53依赖性凋亡至关重要。此外，我们的实证研究表明，p53的乙酰基-K120同工型富含促凋亡靶基因，但不富含细胞周期停滞靶标。此外，乙酰化位点对精氨酸（K120R）的保守突变抑制凋亡，而不会阻止G1停滞。值得注意的是，在少数人肿瘤中已经报道了K120R突变对p53的失活，并且在人类肿瘤中也丢失了催化K120乙酰化的酶（即HMOF和TIP60）。这些观察结果表明，K120-乙酰化途径的激活可能是重要的肿瘤抑制机制。我们当前的模型表明，在DNA损伤后，在K120处的Myst家族蛋白乙酰化p53，然后通过p53选择性地增强丙凋亡靶基因的转录。使用最近开发的工具和方法论，我们生成了全基因组数据集，这将使我们能够识别由p53的AC-K120同工型绑定和调节的所有基因座。此处提出的研究将对K120乙酰化途径在p53功能中扮演的作用提供透彻的理解。我们的最终目标是获得足够的了解，我们将能够以可预测的方式操纵这一途径，以选择性地触发人类癌细胞中的凋亡。