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

 描述（由申请人提供）：心血管疾病（CVD）是工业化国家死亡和残疾的主要原因，其患病率在发展中国家迅速上升。特别地，心力衰竭（HF）已被挑选出来作为流行病，并且是与显著的发病率、死亡率和医疗保健相关的惊人的临床和公共卫生问题 支出。目前的治疗方法只能延迟慢性收缩性心力衰竭患者的发病率和死亡率，因为疾病进展通常持续不减，导致死亡。心力衰竭的新疗法是迫切需要的，这将需要更好地了解这种疾病的潜在分子机制。衰竭心脏的一个普遍特征是通过肌浆网（SR）的Ca 2+循环受损，肌浆网是心肌细胞中Ca 2+的主要内部储存。事实上，来自衰竭心脏的心肌细胞始终显示出缺陷性兴奋收缩偶联，其特征在于减少的SR Ca 2+螯合和减少的细胞内Ca 2+瞬变，这些事件导致收缩性和舒张受损，最终导致心脏的泵送作用降低。Ca 2+再螯合到SR中由Ca 2 +-ATP酶（SERCA）介导，已知其活性由小的整合膜蛋白受磷蛋白（PLN）和肌磷脂（SLN）可逆地调节。增强SERCA活性和功能已被认为是治疗HF的重要临床方法，其通过使SR负载更高的Ca 2+水平以增加Ca 2+释放，从而导致收缩期间更大的肌细胞收缩性。除了基因治疗实际上取代SERCA蛋白（目前在人类临床试验中使用AAV载体），我们目前缺乏一种简单的治疗方法，旨在纠正心脏中Ca 2+和SERCA功能的改变。然而，通过操作PLN或类似的小肽来调节SERCA活性代表了一种新颖且简单的治疗方法。我们的实验室已经鉴定了一种新的由肌肉特异性RNA编码的微肽，目前被注释为长非编码RNA（lncRNA），我们将其命名为DWORF（DWarf开放阅读框架）。DWORF与已被充分描述的SERCA抑制剂PLN和SLN具有很强的序列同源性和预测的结构域结构，我们的初步结果表明它定位于SR并可直接结合SERCA。我们假设DWORF与PLN和SLN在功能上同源，并且它调节SERCA活性和肌细胞收缩性。我们将利用生物化学，细胞为基础的，和遗传学的方法，沿着在体内的生理研究，以确定在心脏的功能和调节DWORF，并检查它如何可能影响心脏疾病的易感性。总的来说，我们的研究将为心脏中的Ca 2+循环和调节提供新的见解，并可能为开发心血管疾病的新治疗靶点提供基础。

 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.