Reprogramming of cardiac genome by Smyd1 in hypertrophy and failure

描述(由申请人提供)：现在人们意识到基因组是动态的，DNA的选择性包装控制着细胞中不同的基因集的表达。DNA包裹在核小体周围并将其组织成更高级的结构从根本上受到染色质重塑酶的影响。这些酶选择性地沿着DNA链定位核小体，并通过修饰组蛋白的氨基末端尾巴来影响组蛋白与DNA的相互作用。染色质结构的巨大变化在发育过程中最为突出，并通过建立特定细胞类型的基因表达来影响细胞命运。在疾病过程中也观察到染色质结构的变化，染色质重塑酶的破坏与心肌肥厚有关。然而，需要清楚地了解调控心脏染色质结构的蛋白质网络，以了解疾病期间基因表达是如何在全基因组范围内重新编程的。尽管组蛋白的翻译后修饰(PTM)已经得到了很好的证实，但负责选择性添加和移除这些调节标记的酶才刚刚开始表征。一个新出现的组蛋白甲基转移酶(HMTs)家族称为SMID。由于心脏分化受损，肌肉限制性家族成员Smyd1的胚系缺失会导致胚胎死亡。与此观察一致的是，在肌肉前体细胞中过表达Smyd1导致了加速分化。尽管对Smyd1在发育过程中的作用有了这些耐人寻味的见解，但它在心脏病中的内源性定位、调节和作用尚不清楚。我的初步数据显示，在心力衰竭期间，Smyd1的丰度增加，并建立了确定其活性、细胞内定位和在这一应用中的作用机制的方法。这项应用的短期目标是了解Smyd1在成人心肌中的作用，并确定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，以了解赋予心脏基因组中Smyd1靶向性的因素。这一应用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促进我们对心力衰竭的理解。我们的方法将提供对HMT的激活和调节的基本见解，以及在它们以基因组为靶点时赋予特异性的机制。对临床领域的意义是为基因组如何在疾病中重新编程提供一个机制基础，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。 公共卫生相关性：心脏病是发达国家的主要死亡原因。这项资助的目标是了解一种名为Smyd1的特定蛋白质如何调节正常心脏中的基因表达，以及疾病期间其功能的变化如何影响心肌肥厚的发展。

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.