Reprogramming of cardiac genome by Smyd1 in hypertrophy and failure

描述（由申请人提供）：现在认识到基因组是动态的，并且DNA的选择性包装控制细胞中不同基因组的表达。核小体周围DNA的包裹及其组织成更高级结构从根本上受到染色质重塑酶的影响。这些酶选择性地将核小体沿着DNA链定位，并通过修饰组蛋白的氨基末端尾部来影响组蛋白与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，并且染色质重塑酶的破坏与心脏肥大有关。 然而，需要清楚地了解调节心脏染色质结构的蛋白质网络，以了解疾病期间基因表达如何在全基因组范围内重新编程。 虽然组蛋白的翻译后修饰（PTM）已经很好地建立，负责选择性添加和删除这些监管标志的酶才开始被表征。 一个新出现的组蛋白甲基转移酶（HMTs）家族被称为Smyd。 肌肉限制性家族成员Smyd1的种系缺失导致心脏分化受损导致胚胎死亡。 与这一观察结果一致，Smyd1在肌肉前体细胞中的过表达导致加速分化。尽管Smyd1在发育过程中的作用有这些有趣的见解，但其内源性定位，调节和在心脏疾病中的作用尚不清楚。 我的初步数据表明，增加Smyd1丰度在心力衰竭，并建立方法来确定其活动，细胞内定位和在此应用中的作用机制。 本申请的短期目标是了解Smyd1在成人心肌中的作用，并表征心力衰竭期间其下游靶点。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的激活和调节以及赋予其靶向基因组特异性的机制提供基本见解。对临床领域的意义是为基因组如何随着疾病重新编程提供机制基础，使得未来的干预可以在治疗上靶向特定的染色质重塑事件。 公共卫生相关性：心脏病是发达国家的主要死因。这项资助的目的是了解一种名为Smyd1的特定蛋白质如何调节正常心脏中基因的表达，以及疾病期间其功能的变化如何影响心脏肥大的发展。

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.