Smyd1's role in regulating disease-induced remodeling and gene expression in the cardiomyocyte

项目摘要 心力衰竭是发达国家死亡的主要原因，其特征是肌细胞生长， 纤维化和器官重塑，并伴随着肌细胞基因组中的转录变化。这些 基因表达的整体变化，包括适应性和适应不良的重编程， 通过染色质的结构变化。虽然许多表观遗传因素已被确定，影响这些 转录变化，负责调节染色质的蛋白质及其随后对 心脏病期间的细胞和器官重塑在很大程度上是未知的。一个关键的机制来改变 染色质结构是通过组蛋白修饰和利用组蛋白去乙酰化酶抑制剂的早期研究 显示在动物模型中治疗后心脏病进展可以减弱，尽管 这些蛋白质的普遍表达和抑制剂的非特异性性质使它们变得不可行 作为一种心脏治疗工具。相比之下，Smyd 1是一种独特的肌细胞特异性组蛋白 调节心肌细胞基因表达的甲基转移酶。它最初被证明在 早期心脏发育，然而最近，我们已经确定Smyd 1是差异调节的， 在人类心力衰竭患者和心脏病小鼠模型中。此外，我们已经证明， 成年小鼠心脏中Smyd 1的缺失导致促肥大信号传导，导致肌细胞生长、纤维化 功能衰退。此外，我们检测了两种Smyd 1亚型，Smyd 1a和Smyd 1b，在分离的 结果表明，Smyd 1a过表达能够抑制苯肾上腺素诱导的心肌细胞凋亡。 肥厚为了建立在这项工作的基础上，我将（目的1）确定Smyd 1a在心脏中的过表达是否能够 使用新的转基因小鼠模型抑制疾病诱导的重塑，并且（目的2）鉴定特异性 基因组中被Smyd 1修饰的基因，以使用染色质调节心肌中的肥大信号传导 免疫沉淀和下一代DNA测序（ChIP-Seq）。这个提议将使我能够 确定Smyd 1在成人心脏中的功能，评估其在减轻心脏病中的作用， 调节肌细胞生长的分子机制。总的来说，这些实验将提高我们的 了解染色质重塑中的整体变化如何协调以及它们如何影响心脏 在心脏病的发展过程中的表型。

Project Summary Heart failure is the leading cause of death in developed countries and is characterized by myocyte growth, fibrosis and organ remodeling, and is accompanied by transcriptional changes in the myocyte genome. These global changes in gene expression, which constitute both adaptive and maladaptive reprogramming, are driven by structural changes in chromatin. Although many epigenetic factors have been identified that influence these transcriptional changes, the proteins responsible for regulating chromatin and their subsequent effects on cellular and organ remodeling during heart disease are largely unknown. One key mechanism to alter chromatin structure is through histone modifications and early studies utilizing histone deacetylase inhibitors revealed that heart disease progression could be attenuated upon treatment in animal models, although the ubiquitous expression of these proteins and the non-specific nature of the inhibitors has made them unfeasible as a therapeutic tool in the heart, thus far. In contrast, Smyd1, is a unique myocyte-specific histone methyltransferase that regulates gene expression in the cardiomyocyte. It was originally shown to play a role in early cardiac development, however more recently, we have determined that Smyd1 is differentially regulated in human heart failure patients and in mouse models of heart disease. In addition, we have demonstrated that loss of Smyd1 in the adult mouse heart leads to pro-hypertrophic signaling resulting in myocyte growth, fibrosis and functional decline. Additionally, we examined the two Smyd1 isoforms, Smyd1a and Smyd1b, in isolated myocytes and showed that Smyd1a overexpression was capable of inhibiting phenylephrine-induced hypertrophy. To build upon this work I will (Aim 1) determine if overexpression of Smyd1a in the heart is able to inhibit disease-induced remodeling using a novel transgenic mouse model, and (Aim 2) identify the specific genes modified by Smyd1 in the genome to regulate hypertrophic signaling in the myocardium using chromatin immunoprecipitation and next-generation DNA sequencing (ChIP-Seq). This proposal will allow me to determine the function of Smyd1 in the adult heart, evaluate its role in attenuating heart disease and identify the molecular mechanisms by which myocyte growth is regulated. Overall these experiments will enhance our understanding of how global changes in chromatin remodeling are coordinated and how they affect cardiac phenotype during the development of heart disease.