Deciphering the role of a novel micropeptide in cardiac function and dysfunction

项目摘要/摘要 钙离子通过作为肌节收缩机械的主要调节器和AS来控制心脏功能 信号转导通路中的第二信使，控制心脏的生长、代谢和 病理性重构。肌浆中的钙泵严格调节横纹肌中的钙处理 维持细胞内钙离子水平的网状(SR)和质膜比 胞外浓度和SR浓度。肌质网膜钙释放一过性增加心肌细胞内钙离子水平 胞浆，触发肌球蛋白在肌节内的跨桥形成，产生收缩力量。 肌浆网钙-三磷酸腺苷酶(SERCA)对肌浆网钙的再摄取是肌肉所必需的 松弛和恢复肌质网钙离子水平，用于随后的收缩-松弛循环。因此，SERCA作为一个 心脏功能的中央调节器，以及驱动心脏病的致病信号级联反应。这个 心脏中SERCA的活性受与SERCA相互作用的小肽--磷蛋白(PLN)的调节 并降低肌浆网钙泵的活性。我们发现一种心脏特异的RNA注释为 因为一个长的非编码RNA实际上编码了一个以前不被识别的微肽，我们称之为DWORF (侏儒开放阅读框架)。在最初的资助期间，我们表明DWORF具有更高的约束力 对SERCA的亲和力优于PLN，且DWORF过表达可缓解相关的收缩功能障碍 PLN过表达，证实其作为SERCA的有效激活剂的作用。此外，使用鼠标 在扩张型心肌病模型上，我们发现DWORF过表达可以恢复心功能和 防止病理重塑和钙离子失调。我们的结果证实了DWORF是一种有效的 它是心脏内SERCA的激活剂，是治疗心力衰竭的有吸引力的候选药物。最近，我们 发现了两种与PLN相关的微肽，称为内调素(ELN)和另一种调节素(ALN)，它们 与特定的SERCA亚型相关，提示它们参与了SERCA依赖的钙信号转导。 总而言之，我们将这一家族的抑制性SERCA微肽称为调节素。我们发现的DWORF- 调节素微肽为我们理解心脏疾病的机制提供了新的途径。 收缩功能和微肽在心血管控制中的未知作用 生理学和病理学。我们的假设是，DWORF-Reglin微肽对细胞至关重要 疾病中的动态平衡和应激适应，因此这些微肽可以作为治疗的靶点 用于心血管和新陈代谢疾病。这项提案的总体目标是定义功能和 DWORF和Regulins在心血管系统中的调节蛋白-蛋白质相互作用及其评价 治疗意义。

Project Summary/Abstract Ca2+ controls cardiac function by acting as the primary regulator of the sarcomeric contractile machinery and as a second messenger in the signal transduction pathways that control cardiac growth, metabolism and pathological remodeling. Ca2+ handling in striated muscle is tightly regulated by Ca2+ pumps in the sarcoplasmic reticulum (SR) and plasma membranes that maintain intracellular Ca2+ levels ~10,000-fold lower than extracellular and SR concentrations. Ca2+ release from the SR membrane transiently increases Ca2+ levels in the cytosol, triggering actomyosin cross-bridge formation within the sarcomere to generate contractile force. Reuptake of Ca2+ into the SR by sarcoplasmic reticulum Ca2+-ATPase (SERCA) is necessary for muscle relaxation and restores SR Ca2+ levels for subsequent contraction-relaxation cycles. SERCA thus serves as a central regulator of cardiac function, as well as the pathogenic signaling cascades that drive heart disease. The activity of SERCA in the heart is modulated by phospholamban (PLN), a tiny peptide that interacts with SERCA in the SR membrane and diminishes Ca2+ pump activity. We discovered that a cardiac-specific RNA annotated as a long noncoding RNA actually encodes a previously unrecognized micropeptide, which we named DWORF (Dwarf Open Reading Frame). During the initial funding period we showed that DWORF has a higher binding affinity for SERCA than PLN and that DWORF overexpression mitigates the contractile dysfunction associated with PLN overexpression, substantiating its role as a potent activator of SERCA. Additionally, using a mouse model of dilated cardiomyopathy, we showed that DWORF overexpression restores cardiac function and prevents the pathological remodeling and Ca2+ dysregulation. Our results established DWORF as a potent activator of SERCA within the heart and as an attractive candidate for a heart failure therapeutic. Recently, we discovered two PLN-related micropeptides, referred to as Endoregulin (ELN) and Another-regulin (ALN), which associate with specific SERCA isoforms, suggesting their involvement in SERCA-dependent Ca2+ signaling. Collectively, we refer to this family of inhibitory SERCA micropeptides as Regulins. Our discovery of the DWORF- Regulin micropeptides provides new inroads into our understanding of the mechanisms involved in cardiac contractility and function and points to unexplored roles of micropeptides in the control of cardiovascular physiology and pathology. Our hypothesis is that DWORF-Regulin micropeptides are critical for cellular homeostasis and stress adaptation in disease, such that these micropeptides can serve as therapeutic targets for cardiovascular and metabolic diseases. The overall goals of this proposal are to define the functions and regulatory protein-protein interactions of DWORF and Regulins in the cardiovascular system and evaluate their therapeutic significance.