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

项目总结/摘要 Ca 2+通过作为肌节收缩机制的主要调节剂和作为 信号转导通路中的第二信使，控制心脏生长、代谢和 病理性重塑横纹肌中的Ca 2+处理受到肌浆中Ca 2+泵的严格调节 网织膜（SR）和质膜，维持细胞内Ca 2+水平低于约10，000倍， 细胞外和SR浓度。从SR膜释放的Ca 2+瞬时增加了细胞中的Ca 2+水平。 胞质溶胶，触发肌节内肌动球蛋白跨桥形成以产生收缩力。 肌浆网Ca ~（2+）-ATP酶（SERCA）对肌浆网Ca ~（2+）的重摄取是肌肉运动的必要条件。 松弛并恢复SR Ca 2+水平用于随后的收缩-松弛循环。因此，SERCA作为 心脏功能的中央调节器，以及驱动心脏病的致病信号级联。的 心脏中SERCA的活性由受磷蛋白（PLN）调节，受磷蛋白是一种与SERCA相互作用的微小肽 在SR膜和减少Ca 2+泵活性。我们发现一种心脏特异性RNA， 作为一个长的非编码RNA实际上编码一个以前未被识别的微肽，我们命名为DWORF （矮型开放式阅读框架）。在最初的资助期间，我们表明DWORF具有更高的约束力， 与PLN相比，DWORF对SERCA的亲和力更高，并且DWORF过表达减轻了与 与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中，我们发现DWORF过表达恢复了心脏功能， 防止病理性重构和Ca 2+失调。我们的研究结果确立了DWORF作为一种有效的 因此，它是心脏内SERCA的激活剂，并且是心力衰竭治疗剂的有吸引力的候选者。最近我们 发现了两种PLN相关的微肽，称为Endoregulin（ELN）和Another-regulin（ALN）， 与特定的SERCA亚型相关，表明它们参与了SERCA依赖的Ca 2+信号传导。 总的来说，我们将这个抑制性SERCA微肽家族称为调节蛋白。我们对DWORF的发现- 调节素微肽为我们理解心脏调节机制提供了新的进展， 收缩性和功能，并指出未探索的作用，在控制心血管疾病的微肽 生理学和病理学。我们的假设是DWORF-调节蛋白微肽对细胞增殖至关重要。 因此，这些微肽可以作为治疗靶点 治疗心血管和代谢疾病本提案的总体目标是界定职能， DWORF和调节蛋白在心血管系统中的调节蛋白-蛋白相互作用，并评估其 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.