The metabolically-induced epigenetic memory as a Regulator of myocardial stress response

对心脏病的个性化诊断和治疗方法的挑战是疾病过程中的个体差异和个体不同的危险因素。心脏病的一个危险因素是超重和相关的全身变化，这被概括为“代谢综合征”。除了每个病人不可避免地带来的遗传先决条件外，他/她还经历了他/她生命中促进疾病或健康的一些阶段（例如肥胖、吸烟或大量体育活动的阶段）。这种个体病史可能会影响心脏对未来压力情况的反应（例如儿茶酚胺）。这种观察的分子机制尚未在心脏中得到可靠的证实。表观遗传改变可以导致病理基因或保护基因的改变，从而使它们在压力情况下表现不同。有一类特定的基因组区域，即增强子，在这里是特别有趣的。它们不仅调节一个基因的转录，而且由于DNA的三维折叠，它们还可以与多个基因相互作用。转录激活总是先于增强子激活，因此可以在没有直接表达改变（或可测量的临床表型）的情况下永久改变。在初步实验中，我们给小鼠喂食高脂肪饮食（HFD），并将它们与从高脂肪饮食转变为正常饮食（HFLFD）的小鼠进行比较。利用活性增强子的染色质免疫沉淀，我们发现了一个基因组区域，即使小鼠的表型（超重）从HFD切换到LFD（正常体重）后恢复到完全正常，该区域在HFD治疗的动物中仍处于开启状态。该区域包含两个增强子（代谢增强子1和2；ME1/2）和一个编码基因（Id1）。利用CRISPR/Cas9，我们基因删除了心肌细胞（E1-cKO; E2-cKO）中的ME1和ME2以及Id1。Id1-cKO)。条件Id1基因敲除小鼠在4个月大时表现出心功能下降。目前尚不清楚ME1（或ME2）在多大程度上调节Id1的表达，以及应激条件下成人心脏中Id1失调的后果。本研究的目的是进一步研究ME1和ME2在心肌细胞表观遗传记忆中的作用。具体目标是：1：高脂肪饮食和儿茶酚胺能应激下E1-cKO、E2-cKO和Id1-cKO条件敲除系的特征。2 . ME1和ME23蛋白基因组相互作用伙伴的鉴定：表观遗传记忆激活（ME1/2）在体内对儿茶酚胺能应激反应中的重要性

Challenges for a personalized diagnostic and therapeutic approach to cardiac diseases are the interindividual differences in the course of the disease and the individually different risk factors. One risk factor for cardiac diseases is overweight and the associated systemic changes, which are summarized under the term 'metabolic syndrome'. In addition to the genetic preconditions that every patient inevitably brings with him/her, he/she goes through a number of phases in his/her life that promote illness or health (e.g. phases of obesity, smoking or extensive sporting activity). This individual history may influence the heart's reaction to future stress situations (e.g. catecholamines). A molecular mechanism of this observation has not yet been reliably proven in the heart. Epigenetic alterations can lead to modifications of pathological or protective genes, so that they behave differently in stress situations. A certain class of genomic regions, the enhancers, are of particular interest here. They not only regulate the transcription of one gene, but can also interact with multiple genes due to the 3-dimensional folding of DNA. Transcriptional activation is always preceded by enhancer activation, and can therefore be permanently altered without direct expression changes (or measurable clinical phenotype). In preliminary experiments, we have fed mice on a high-fat diet (HFD) and compared them with mice that underwent a change from HFD to a normal diet (HFLFD). Using chromatin immunoprecipitation of active enhancers, we identified a genomic region that is switched on in HFD-treated animals and remains switched on even if the phenotype (overweight) of the mouse returns to completely normal after switching from HFD to LFD (normal weight). This region contains two enhancers (metabolic enhancers 1 and 2; ME1/2) and a coding gene (Id1). Using CRISPR/Cas9 we have genetically deleted ME1 and ME2 as well as Id1 in cardiomyocytes (E1-cKO; E2-cKO. Id1-cKO). Conditional Id1 knockout mice show reduced cardiac function at the age of 4 months. It is unclear to what extent ME1 (or ME2) regulate the expression of Id1 and what consequences dysregulation of Id1 has in the adult heart under stress conditions. The aim of the present proposal is to further investigate the role of ME1 and ME2 for epigenetic memory in cardiomyocytes. Specific objectives are:1: Characterization of conditional knockout lines for E1-cKO, E2-cKO and Id1-cKO under high-fat diets and catecholaminergic stress.2: Identification of the proteo-genomic interaction partners of ME1 and ME23: Importance of epigenetic memory activation (ME1/2) in vivo for the response to catecholaminergic stress