Transcription Programming in Cardiac Growth

心脏生长中的转录编程

基本信息

批准号：
7076132
负责人：
Nanette Hahr Bishopric
金额：
$ 36.78万
依托单位：
UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-07-01 至 2008-06-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The transcriptional coactivator and histone acetyltransferase p300 was originally identified as a cellular target of adenovirus E1A, and has been implicated in many basic cell functions including proliferation, differentiation and tissue-specific gene expression. Others and we have shown that myocardial growth, development, and gene expression are extremely sensitive to p300 levels. Myocardial hypertrophy is associated with marked increases in p300 levels. To investigate the significance of this increase, we have generated 6 strains of transgenic mice with myocardial overexpression of p300 (1.5 to 5-fold of endogenous levels). All 6 strains develop severe cardiac hypertrophy, and progress to heart failure in a manner that is proportionate to their p300 levels and cardiac workload. Mice with haploinsufficiency of p300 have a markedly reduced hypertrophic response to pressure overload, and do not develop heart failure. These findings indicate that p300 plays a critical role in the induction of hypertrophy and the transition to heart failure. The objective of this proposal is to identify the molecular mechanisms underlying the role of p300 in hypertrophy. A widely accepted model for p300 function predicts that transcription factors compete for a limiting supply of p300. For example, Jun (AP-1) and MyoD1 engage in competitive transcription activation depending on the availability of p300. The current proposal will test the hypothesis that an increase in p300 supply is both sufficient and necessary for hypertrophic growth of the myocardium, through relief of a competitive interaction between growth-promoting and muscle-specific transcription programs. A corollary is that sustained activation of p3OO-dependent growth pathways leads to disordered myocardial growth and apoptosis. The requirement for p300 in hypertrophy will be tested in complementary mouse strains expressing inducible, cardiac-restricted wild type and specific domain-deleted p300 transgenes. We will characterize the functions and regulatory motifs of myocardial genes targeted by p300 in vivo, by the concerted use of genome-wide transcription profiling, chromatin immunoprecipitation assays, and quantitative RNA analysis, in mice with p300 gain- and loss-of-function. Finally, we will examine the functional effects of p300 availability on cardiomyocyte proliferation and apoptosis susceptibility. These experiments will identify critical mechanisms underlying cardiac hypertrophy and failure, and illuminate the role of p300 in hypertrophic growth of the cell.

描述（由申请人提供）：转录共激活因子和组蛋白乙酰转移酶P300最初被鉴定为腺病毒E1A的细胞靶标，并且与许多基本细胞功能有关，包括增殖，分化和组织特异性基因表达。其他人则表明，心肌生长，发育和基因表达对P300水平极为敏感。心肌肥大与P300水平的明显增加有关。为了研究这种增加的重要性，我们已经产生了6菌株的转基因小鼠，其心肌过表达为P300（内源性水平为1.5至5倍）。所有6株菌株都会以与P300水平成比例的方式和心脏工作量相称的方式发展为心力衰竭。 p300的单倍不足的小鼠对压力超负荷的肥大反应明显降低，并且不会产生心力衰竭。这些发现表明，p300在肥大诱导和心力衰竭的过渡中起着至关重要的作用。该建议的目的是确定p300在肥大中作用的分子机制。 P300功能的广泛接受的模型预测，转录因子竞争P300的限制供应。例如，JUN（AP-1）和MYOD1根据P300的可用性进行竞争性转录激活。当前的提案将检验以下假设：通过缓解增长促进和肌肉特异性的转录程序之间的竞争相互作用，P300供应量增加对于心肌的肥厚型生长既足够且必要。推论的是，p3oo依赖性生长途径的持续激活会导致心肌生长和凋亡。 P300在肥大中的需求将以表达诱导，心脏限制的野生型和特定域污染的P300转基因的互补小鼠菌株进行测试。我们将通过在具有P300增益和功能丧失的小鼠中协同使用全基因组的转录分析，染色质免疫沉淀测定法和定量RNA分析来表征由P300在体内靶向的心肌基因的功能和调节基序。最后，我们将研究p300可用性对心肌细胞增殖和凋亡易感性的功能影响。这些实验将确定心脏肥大和失败的基础的关键机制，并阐明p300在细胞肥大生长中的作用。