Elucidation of the Role of a Novel Cardiac Micropeptide in the Control of Heart Function and Dysfunction

 描述(申请人提供)：心血管疾病(CVD)是工业化国家导致死亡和残疾的主要原因，在发展中国家其患病率正在迅速上升。特别是，心力衰竭(Hf)已被单独列为一种流行病，是一个令人震惊的临床和公共卫生问题，与显著的发病率、死亡率和医疗保健有关。 支出。目前的治疗方法只延缓了慢性收缩性心力衰竭患者的发病率和死亡率，因为疾病的进展通常会有增无减，导致死亡。迫切需要治疗心力衰竭的新疗法，这将需要更多地了解这种疾病背后的潜在分子机制。衰竭心脏的一个普遍特征是通过肌浆网(SR)的钙循环受损，肌浆网是心肌细胞中钙的主要内部存储。事实上，衰竭心脏的心肌细胞始终表现出兴奋收缩偶联缺陷，其特征是肌浆网钙封存减少和细胞内钙瞬变减少，这些事件导致收缩和松弛能力受损，最终导致心脏泵血活动受抑。Ca~(2+)-ATPase(SERCA)是由Ca~(2+)-ATPase(SERCA)介导的，其活性受小分子膜蛋白磷蛋白(PLN)和肌磷脂(SLN)的可逆调节。增强SERCA的活性和功能被认为是治疗HF的重要临床方法，通过增加SR中更高的Ca~(2+)水平来增加Ca~(2+)的释放，从而在收缩期间增加心肌细胞的收缩能力。除了基因疗法来真正取代SERCA蛋白(目前正在用AAV载体进行人类临床试验)外，我们目前还缺乏一种简单的治疗方法，旨在纠正心脏中钙离子和SERCA功能的变化。然而，通过操纵PLN或类似的小肽来调节SERCA的活性代表了一种新的和直接的治疗方法。我们的实验室已经发现了一种由肌肉特异性RNA编码的新型微肽，目前被注释为长非编码RNA(LncRNA)，我们将其命名为DWORF(侏儒开放阅读框架)。DWORF与SERCA抑制剂PLN和SLN有很强的序列同源性和预测的结构域结构，初步结果表明它定位于SR并可以直接与SERCA结合。我们假设DWORF在功能上与PLN和SLN同源，并调节SERCA活性和心肌细胞收缩。我们将利用生化、基于细胞和遗传学的方法，以及体内的生理学研究来定义DWORF在心脏中的功能和调节，并研究它可能如何影响心脏疾病的易感性。总而言之，我们的研究将为心脏中的钙循环和调节提供新的见解，并可能为开发新的心血管疾病治疗靶点提供基础。

 DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) is the leading cause of death and disability in industrialized nations and its prevalence is rising rapidly in developing nations. In particular, heart failure (HF) has been singled out as an epidemic and is a staggering clinical and public health problem associated with significant morbidity, mortality, and healthcare expenditures. Current therapies only delay morbidity and mortality in patients with chronic systolic heart failure, as disease progression typically continues unabated resulting in death. Novel therapies for heart failure are desperately needed, which will require a greater understanding of the underlying molecular mechanisms that underlie this disease. A universal characteristic of the failing heart is impaired Ca2+ cycling through the sarcoplasmic reticulum (SR), the major internal store of Ca2+ in cardiomyocytes. Indeed, cardiomyocytes from failing hearts consistently show defective excitation contraction-coupling characterized by diminished SR Ca2+ sequestration and decreased intracellular Ca2+ transients, events that contribute to impaired contractility and relaxation that culminate in depressed pumping action of the heart. Ca2+ re- sequestration into the SR is mediated by a Ca2+-ATPase (SERCA), whose activity is known to be reversibly regulated by the small integral membrane proteins phospholamban (PLN) and sarcolipin (SLN). Enhancing SERCA activity and function has been suggested as an important clinical approach for treating HF by loading the SR with greater Ca2+ levels to augment Ca2+ release resulting in greater myocyte contractility during systole. Apart from gene therapy to actually replace SERCA protein (which is currently in human clinical trails with an AAV vector), we currently lack a facile therapeutic approach aimed at correcting alterations in Ca2+ and SERCA function in the heart. However, modulation of SERCA activity through manipulation of PLN or small peptides like it represents a novel and straightforward therapeutic approach. Our lab has identified a novel micropeptide encoded by a muscle-specific RNA currently annotated as a long non-coding RNA (lncRNA), which we have named DWORF (DWarf Open Reading Frame). DWORF shares strong sequence homology and predicted domain structure with the well-described SERCA inhibitors PLN and SLN and our preliminary results show it localizes to the SR and can bind directly to SERCA. We hypothesize that DWORF is functionally homologous to PLN and SLN and that it regulates SERCA activity and myocyte contractility. We will utilize biochemical, cell-based, and genetic approaches, along with in vivo physiological studies to define the function and regulation of DWORF in the heart and to examine how it might impact cardiac disease susceptibility. Collectively, our studies will provide new insights into Ca2+ cycling and regulation in the heart and potentially provide the basis for development of a novel therapeutic target in cardiovascular disease.