Role of the Acetyltransferase p300 in Cellular Responses

乙酰转移酶 p300 在细胞反应中的作用

基本信息

批准号：
7104292
负责人：
MARIA L AVANTAGGIATI
金额：
$ 30.35万
依托单位：
GEORGETOWN UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-08-06 至 2008-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Drugs that affects the microtubule dynamics constitute one of the most important classes of chemotherapeutic agents. Anti-microtubule drugs of clinical relevance include paclitaxel (taxol), vinca alkaloids (vinblastin and vincrisitn), nocodazole and colchicine. These agents trigger a checkpoint, the spindle checkpoint, which monitors he attachment of chromosomes to the spindle, and elicits arrest in mitosis generally followed by apoptosis. Several cellular factors which participate in this checkpoint have recently been identified, however, the exact molecular mechanisms through which errors in spindle assembly, or chromosomes attachment to the spindle engage the cell cycle machinery remain to be elucidated. We made the novel finding that a transcription coactivator possessing acetyltransferase activity, p300, enhances the mitotic arrest elicited by taxol. Acetyltransferases belonging to the p300 family have been implicated in conveying adaptive responses in a variety of signal transduction pathways, through regulation of transcription of many cell-cycle regulatory genes. We now demonstrate that p300 associates with mitotic and interphase microtubules, it acetylates tubulin, and it favors tubulin polymerization in a taxol-dependent assay. Moreover p300 levels and its association with microtubules are significantly increased in taxol treated cells. Based on these results we hypothesize that p300 acts as an important effector of sensitivity of tumor cells to taxol, through its association with tubulin and through its activity as a transcription factor. To test this hypothesis we will: l)Identify the regions of p300 responsible for its interaction with microtubules and generate mutants with corrupted tubulin-binding ability (loss or gain of function, respectively). 2) Study how these mutants influence cytoskeleton architecture, spindle assembly and nuclear import of acetylated transcription factors in taxol treated cells. 3)Define the mechanisms by which p300 participates in cell cycle arrest and apoptosis induced by taxol and identify the molecular events occurring downstream of taxol which are influenced by p300. 4)Provide a rationale and a strategy for the design of molecules, such as peptides which mimics p300 effects on apoptosis, able to enhance chemosensitivity to taxol. Since mitotic spindle inhibitors constitute a growing class of anti-cancer agents, it is essential to understand molecular mechanisms of resistance and sensitivity. Thus, studies proposed in this application are expected to have important clinical implications.

描述（由申请人提供）：影响微管动力学的药物构成了最重要的化学治疗剂类别之一。临床相关性的抗微管药物包括紫杉醇（紫杉醇），VINCA生物碱（Vinblastin和Vincrisitn），诺科唑和秋水仙碱。这些试剂触发了一个检查点，主轴检查点，该检查点监测染色体附着在纺锤体上，并在有丝分裂中引起抑制，然后通常会凋亡。最近已经确定了参与该检查点的几个细胞因子，但是，纺锤体组装中误差的确切分子机制，或者在纺锤体上的染色体附着在纺锤体上接触细胞循环机制仍有待阐明。我们提出了一个新的发现，即具有乙酰转移酶活性P300的转录共激活因子增强了紫杉醇引起的有丝分裂骤停。属于P300家族的乙酰基转移酶与通过调节许多细胞周期调节基因的转录来传达各种信号转导途径中的适应性反应。现在，我们证明了p300与有丝分裂和相间微管，IT乙酰化微管相关联，并且在符合紫杉醇依赖性测定中有利于微管蛋白聚合。此外，P300水平及其与微管的关联在经紫杉醇处理的细胞中显着增加。基于这些结果，我们假设p300通过其与微管蛋白的关联以及通过其作为转录因子的活性来充当肿瘤细胞敏感性的重要效果。为了检验该假设，我们将：l）确定p300与微管相互作用的区域，并生成具有损坏的小管蛋白结合能力（分别损失或功能获得）的突变体。 2）研究这些突变体如何影响紫杉醇处理细胞中乙酰化转录因子的细胞骨架结构，纺锤体组装和核进口。 3）定义P300参与紫杉醇引起的细胞周期停滞和凋亡的机制，并确定紫杉醇下游发生的分子事件，受P300的影响。 4）提供理由和策略分子的设计，例如模仿p300对细胞凋亡的肽，能够增强对紫杉醇的化学敏感性。由于有丝分裂纺锤体抑制剂构成了种植的抗癌药，因此必须了解抗性和敏感性的分子机制。因此，预计该应用中提出的研究将具有重要的临床意义。