Mechanisms of YY1 Inhibition of Cardiac Hypertrophy

描述(申请人提供)：心力衰竭是美国最昂贵的医疗问题，也是导致死亡和残疾的主要原因。尽管针对心力衰竭治疗的药物抑制剂在治疗上是有益的，但心力衰竭的频率仍在增加，需要更多的靶点。我们的长期目标是确定转录因子YY1防止病理性心肌肥大的分子机制(S)，并为心脏病的预防提供有价值的靶点。YY1是一种普遍存在的转录因子，调节多个基因的表达。YY1已被证明主要是肌肉基因的抑制因子。我们有强有力的初步数据表明，YY1可以防止伴随心肌肥大而来的细胞变化。YY1通过与第二类组蛋白脱乙酰酶(HDAC)结合并保留在细胞核中，防止α和β肾上腺素能刺激反应中胎儿基因表达的异构体上调。本研究的目的是：(1)明确YY1抑制HDAC4和5核输出的机制；(2)分析YY1与胎儿基因启动子在不同肥大刺激下的相互作用；(3)在病理性心肌肥厚的活体模型系统中研究YY1过表达的影响。目的通过分析YY1-HDAC相互作用结构域，将含有相互作用结构域的载体导入新生心肌细胞，分析其基因表达、细胞肥大和HDACs4、5的定位。目的通过对YY1和各种胎儿基因启动子的染色质免疫沉淀来实现对肥大刺激的反应。目的通过建立YY1过表达的条件性转基因小鼠模型来实现。这些动物将通过植入含有肥大激动剂的微型渗透泵来诱导肥大，并将分析心脏功能和细胞肥大的变化。这些研究揭示的数据将迅速促进我们对病理性心肌肥厚发生的信号成分的理解。

DESCRIPTION (provided by applicant): Heart failure is the most expensive medical problem in the United States, and a major cause of death and disability. Although pharmacological inhibitors targeted to the treatment of heart failure are therapeutically beneficial, heart failure is still increasing in frequency, and additional targets are needed. Our long term goal is to define the molecular mechanism(s) by which the transcription factor YY1 protects against pathologic cardiac hypertrophy and to provide valuable targets for the prevention of cardiac disease. YY1 is an ubiquitous transcription factor that regulates expression of multiple genes. YY1 has been shown to be mostly a represser of muscle genes. We have strong preliminary data showing that YY1 prevents the cellular changes that accompany cardiac hypertrophy. YY1 prevents up-regulation of the fetal isoforms of gene expression in response to alpha and beta adrenergic stimulation by binding to and retaining in the nucleus class II histone deacetylases (HDACs). The goals of this application are to: (Aim I) identify the mechanism by which YY1 prevents HDACs 4 and 5 nuclear export in response to various hypertrophic agonists; (Aim II) analyze the interaction of YY1 with fetal gene promoters in response to various hypertrophic stimuli (Aim III) characterize the effect of YY1 over-expression in an in vivo model system of pathological cardiac hypertrophy. Aim I will be achieved by analyzing YY1-HDAC interaction domains; constructs containing the interaction domains will be transfected into neonate cardiac myocytes and gene expression, cellular hypertrophy and HDACs 4 and 5 localization will be analyzed. Aim II will be achieved through chromatin immunoprecipitation of YY1 and the various fetal gene promoters in response to hypertrophic stimuli. Aim IV will be achieved by creating a conditional transgenic mouse model of YY1 over-expression. Hypertrophy will be induced in these animals by implantation of mini-osmotic pumps containing hypertrophic agonists, and heart function and changes in cellular hypertrophy will be analyzed. The data revealed from these studies will rapidly progress our understanding of the signaling components responsible for the development of pathologic cardiac hypertrophy.