Role of Nucleoside-Diphosphate Kinase Signaling in Atrial Fibrillation

项目总结/摘要 心房颤动（AF）是最常见的心律失常，与高发病率和死亡率相关，但 由于对潜在机制的不完全理解，仍然难以治疗。新出现的证据 表明核苷二磷酸激酶（NDPKs）在心脏中发挥重要作用，能够 以不依赖于G蛋白受体的方式升高cAMP水平。我们的试验数据表明， 持续性（慢性）AF患者中NDPK-B和NDPK-C亚型的升高与cAMP升高相关 水平，异常肌浆网Ca 2+释放，异位（触发）活动和诱导型AF。 本项目的长期目标是剖析NDPK依赖性心律失常的分子和细胞基础 中心假设是，NDPK-B和NDPK-C水平的提高通过增强AF的发病机制而促进AF。 RyR 2微结构域中的cAMP水平，导致异常的细胞内Ca 2+信号传导，产生底物 房颤的发生、维持和进展。将追求三个具体目标：（1）确定是否 NDPK表达增加是促进自发性AF的必要和充分条件，2）评估是否 升高的NDPK水平通过RyR 2引起cAMP依赖性SR Ca 2+渗漏，和3）确定Ankrd 1的作用 在RyR 2-NDPK信号复合物中。这些研究将在患者的心房肌细胞中进行 与AF，AF的狗模型，和AF的各种心房选择性遗传小鼠模型。 FRET传感器和心房选择性腺相关病毒（AAV 9）介导的基因治疗将用于 解析NDPK-B/C和cAMP在特定细胞微域内的促凋亡作用。这些研究 预计将确定NDPK亚型是否以及如何有助于AF的发展，并作为一种有效的方法。 用于验证NDPK作为预防或治疗AF的新型药物靶点的平台。

PROJECT SUMMARY / ABSTRACT Atrial fibrillation (AF), the most common arrhythmia, is associated with high morbidity and mortality, but remains difficult to treat due to an incomplete understanding of underlying mechanisms. Emerging evidence suggests that nucleoside diphosphate kinases (NDPKs) play an important role in the heart by being able to elevate cAMP levels in a G-protein receptor-independent manner. Our pilot data suggest that increased levels of NDPK-B and NDPK-C isoforms in patients with persistent (chronic) AF are associated with elevated cAMP levels, abnormal sarcoplasmic reticulum Ca2+ releases, ectopic (triggered) activity and inducible AF. The long- term goal of this project is to dissect the molecular and cellular basis of NDPK-dependent arrhythmia mechanisms in AF. The central hypothesis is that enhanced NDPK-B and -C levels promote AF by enhancing cAMP levels in the RyR2 microdomain, resulting in aberrant intracellular Ca2+ signaling that creates a substrate for AF initiation, maintenance, and progression. Three specific aims will be pursued: 1) Determine whether increased NDPK expression is both necessary and sufficient to promote spontaneous AF, 2) Assess whether elevated NDPK levels cause cAMP-dependent SR Ca2+ leak via RyR2, and 3) Determine the role of Ankrd1 within the RyR2-NDPK signaling complex. These studies will be performed in atrial myocytes from patients with AF, a dog model of AF, and various atrial-selective genetic mouse models of AF. Novel targeted cAMP FRET sensors and atrial-selective adeno-associated virus (AAV9)-mediated gene therapy will be utilized to resolve the pro-arrhythmic roles of NDPK-B/C and cAMP within specific cellular microdomains. These studies are expected to establish whether and how NDPK isoforms contributes to AF development and serve as a platform for the validation of NDPKs as novel druggable target for the prevention or treatment of AF.