Transcription Programming in Cardiac Growth

心脏生长中的转录编程

• 批准号: 6769969
• 负责人: Nanette Hahr Bishopric
• 金额: $ 37.66万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6769969
• 关键词: acyltransferase; apoptosis; cardiac myocytes; cardiogenesis; confocal scanning microscopy; echocardiography; electron microscopy; gene expression; genetic transcription; genetically modified animals; heart failure; histogenesis; histones; immunocytochemistry; laboratory rat; microarray technology; northern blottings; polymerase chain reaction; tissue /cell culture; transcription factor; ventricular hypertrophy

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。其他人和我们已经表明，心肌生长、发育和基因表达对 p300 水平极其敏感。心肌肥厚与 p300 水平显着升高相关。为了研究这种增加的意义，我们培育了 6 种心肌 p300 过度表达（内源水平的 1.5 至 5 倍）的转基因小鼠。所有 6 种菌株都会出现严重的心脏肥大，并以与其 p300 水平和心脏负荷成比例的方式进展为心力衰竭。 p300 单倍体不足的小鼠对压力超负荷的肥大反应显着降低，并且不会发展为心力衰竭。这些发现表明 p300 在诱导肥大和向心力衰竭的转变中发挥着关键作用。该提案的目的是确定 p300 在肥大中作用的分子机制。一个被广泛接受的 p300 功能模型预测转录因子会争夺 p300 的有限供应。例如，Jun (AP-1) 和 MyoD1 根据 p300 的可用性参与竞争性转录激活。目前的提案将测试以下假设：通过缓解生长促进和肌肉特异性转录程序之间的竞争性相互作用，p300 供应的增加对于心肌的肥大生长来说是充分且必要的。一个推论是 p3OO 依赖性生长途径的持续激活会导致心肌生长紊乱和细胞凋亡。将在表达可诱导的、心脏限制的野生型和特定结构域删除的 p300 转基因的互补小鼠品系中测试肥大对 p300 的需求。我们将通过在 p300 功能获得和丧失的小鼠中协调使用全基因组转录分析、染色质免疫沉淀分析和定量 RNA 分析，来描述体内 p300 靶向的心肌基因的功能和调节基序。最后，我们将检查 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衰竭的关键机制，并阐明 p300 在细胞肥大生长中的作用。