MOLECULAR POLARIZATION IN DYSSYNCHRONOUS HEARTS AND CRT

这个子项目的重点是确定心脏不同步性在有和没有潜在心力衰竭时导致局部分子和细胞跨壁异常的影响和机制。这个项目源于我们最近的发现，即衰竭心脏的不同步性会导致与钙处理、肥大信号和电传导相关的蛋白质表达的显著局部变化。这些变化尤其集中在晚期激活区域的心内膜层，该区域预计具有最高的室壁应力水平。邻近的心外膜中层组织的表达更类似于对侧壁(外膜和内膜层)的表达。这突出了局部的跨壁分子极化，它可以作为为什么不同步是心力衰竭患者的主要风险的重要底物。除了更全面地分析心脏衰竭时不同步对心脏分子和细胞的影响外，这个子项目还将通过心脏再同步来测试这些变化的可逆性。有三个具体目标。第一个目标将识别在不同步心脏中触发的信号级联，阐明它们在晚期(高应激)激活的心肌中对心内膜各层的特异性，并确定共存的扩张性心力衰竭的协同作用。使用了两个主要策略：对候选蛋白质/基因进行特定测试 涉及生长、重塑和心肌细胞钙处理，以及对肌细胞亚蛋白质组(胞浆、肌浆网、缝隙连接)和转录组(犬类芯片)的更广泛分析。第二个目标是将这些分子发现与直接分析心肌细胞不同步对细胞功能和钙处理的影响相结合，这些不同步来自心内膜和中壁层的早期和晚期激活区。第三个目的是测试由随后的心脏双室再同步化引起的不同步引起的分子和细胞异常的可逆性。这些研究将提供这种可逆性的第一个测试，并将分子和细胞水平的变化整合到整个器官水平。

This subproject focuses on defining the influence and mechanisms whereby cardiac dyssynchrony with and without underlying cardiac failure induces local molecular and cellular transmural abnormalities. This project stems from our recent discovery that dyssynchrony in a failing heart results in striking localized changes in the expression of proteins involved with calcium handling, hypertrophic signaling, and electrical conduction. These changes are particularly concentrated in the endocardial layer of the late-activated territory, the region predicted to have the highest level of wall stress. Neighboring mid-epicardial tissue displays expression more akin to that observed in the opposing wall (both epi and endo layers). This highlights a localized transmural molecular polarization that can serve as an important substrate for why dyssynchrony is a major risk in heart failure patients. In addition to providing a more comprehensive analysis of the ventricular molecular and cellular effects from dyssynchrony in failure, this subproject will test the reversibility of these changes by means of cardiac resynchronization. There are three specific aims. The first aim will identify signaling cascades triggered in the dyssynchronous heart, clarify their specificity to endocardial layers in late (high stress)-activated myocardium, and determine the synergistic role of co-existing dilated cardiac failure. Two major strategies are used: specific testing of candidate proteins/genes involved with growth, remodeling, and myocyte calcium handing, and a broader analysis of myocyte sub-proteome (cytosolic, sarcomplasmic reticulum, gap junction) and transcriptome (canine array chip). The second aim will integrate these molecular findings with direct analysis of the cellular functional and calcium handling impact of dyssynchrony in cardiomyocytes derived from early versus late activated territories from both endocardial and mid-wall layers. The third aim tests the reversibility of molecular and cellular abnormalities induced by dyssynchrony by a subsequent period of cardiac bi-ventricular resynchronization. These studies will provide the first test of such reversibility, and integrate changes at molecular and cellular levels to at the whole organ level.