Reprogramming of cardiac genome by Smyd1 in hypertrophy and failure

描述（由申请人提供）：现在已经认识到基因组是动态的，DNA的选择性包装控制着细胞中不同基因集的表达。DNA在核小体周围的包裹及其组织成高阶结构从根本上受染色质重塑酶的影响。这些酶选择性地沿DNA链定位核小体，并通过修饰组蛋白的氨基末端尾部影响组蛋白与DNA的相互作用。染色质结构的总体变化在发育过程中最为突出，并通过建立细胞类型特异性基因表达来影响细胞命运。在疾病期间也观察到染色质结构的变化，染色质重塑酶的破坏与心脏肥厚有关。然而，要了解疾病期间基因表达是如何在全基因组范围内重编程的，需要对调节心脏染色质结构的蛋白质网络有一个清晰的认识。虽然组蛋白的翻译后修饰（PTM）已经很好地建立，但负责选择性添加和去除这些调节标记的酶才刚刚开始被表征。一个新出现的组蛋白甲基转移酶（hmt）家族被称为Smyd。肌肉受限家族成员Smyd1的种系缺失会导致心脏分化受损导致胚胎死亡。与这一观察结果一致，肌肉前体细胞中Smyd1的过度表达导致分化加速。尽管对Smyd1在发育过程中的作用有了这些有趣的见解，但其内源性定位、调节和在心脏病中的作用尚不清楚。我的初步数据表明，在心力衰竭期间Smyd1丰度增加，并建立了确定其活性、细胞内定位和作用机制的方法。这项应用的短期目标是了解Smyd1在成人心肌中的作用，并表征其在心力衰竭期间的下游靶点。该项目的长期目标是整合这些概念，以了解心脏基因组中赋予Smyd1靶向特异性的因素。该应用程序利用最先进的蛋白质组学，动物生理学，生物化学，成像和下一代测序技术来推进我们对心力衰竭的理解。我们的方法将为hmt的激活和调控以及赋予其靶向基因组特异性的机制提供基本见解。对临床领域的意义在于为基因组如何与疾病重编程提供了机制基础，以便未来的干预可以针对特定的染色质重塑事件进行治疗。

DESCRIPTION (provided by applicant): It is now appreciated that genomes are dynamic and that selective packing of DNA governs the expression of distinct sets of genes in a cell. The wrapping of DNA around nucleosomes and its organization into higher order structures is fundamentally influenced by chromatin remodeling enzymes. These enzymes selectively position nucleosomes along the DNA strand and influence the interaction of histones with DNA by modifying the amino terminal tails of histones. Gross changes in chromatin structure are most prominent during development and influence cell fate by establishing cell-type-specific gene expression. Changes in chromatin structure have also been observed during disease and disruption of chromatin remodeling enzymes has been implicated in cardiac hypertrophy. However, a clear picture of the protein networks that modulate chromatin architecture in the heart is needed to understand how gene expression is reprogrammed on a genome-wide scale during disease. Although the post-translational modification (PTM) of histones has been well established, the enzymes responsible for the selective addition and removal of these regulatory marks have only begun to be characterized. A newly emerging family of histone methyltransferases (HMTs) is called Smyd. Germline deletion of the muscle-restricted family member, Smyd1, leads to embryonic lethality due to impaired cardiac differentiation. Consistent with this observation, overexpression of Smyd1 in muscle precursor cells led to accelerated differentiation. Despite these intriguing insights into the role of Smyd1 during development, its endogenous localization, regulation and role in cardiac disease are unknown. My preliminary data demonstrate increased Smyd1 abundance during heart failure and establish the approaches to determine its activity, intracellular localization and mechanisms of action in this application. The short term goal of this application is to understand the role of Smyd1 in the adult myocardium and to characterize its downstream targets during heart failure. The long term goal of this project is to integrate these concepts to understand the factors that confer targeting specificity to Smyd1 in the cardiac genome. This application leverages state-of-the-art proteomics, animal physiology, biochemistry, imaging and next generation sequencing technology to advance our understanding of heart failure. Our approach will provide fundamental insights into the activation and regulation of HMTs, as well as the mechanisms that confer specificity in their targeting of the genome. The significance to the clinical realm is to provide a mechanistic basis for how the genome is reprogrammed with disease, such that future interventions can target specific chromatin remodeling events therapeutically. PUBLIC HEALTH RELEVANCE: Heart disease is the leading cause of death in the developed world. The goal of this grant is to understand how a specific protein called Smyd1 modulates the expression of genes in the normal heart and how changes in its function during disease affect the development of cardiac hypertrophy.