Role of Nucleoside-Diphosphate Kinase Signaling in Atrial Fibrillation

项目摘要/摘要 房颤是最常见的心律失常，具有较高的发病率和死亡率，但 由于对潜在机制的不完全了解，仍然很难治疗。新出现的证据 提示核苷二磷酸激酶(NDPKs)在心脏中发挥重要作用，因为它能够 以不依赖G蛋白受体的方式升高cAMP水平。我们的试点数据表明， 持续性(慢性)房颤患者的NDPK-B和NDPK-C亚型与cAMP升高相关 异常的肌浆网钙释放、异位(触发)活动和诱发的房颤。长的- 本项目的学期目标是剖析NDPK依赖性心律失常的分子和细胞基础。 房颤的发生机制。中心假设是增强的NDPK-B和-C水平通过增强 RyR2微区的cAMP水平，导致细胞内钙信号异常，从而产生底物 用于房颤的启动、维持和进展。将追求三个具体目标：1)确定 增加NDPK的表达是促进自发性房颤的必要条件和充分条件，2)评估 NDPK水平升高通过RyR2导致cAMP依赖的SR钙离子泄漏，3)决定Ankrd1的作用 在RyR2-NDPK信号复合体中。这些研究将在患者的心房肌细胞中进行。 有房颤，房颤的狗模型，以及各种房颤的遗传小鼠模型。新颖的靶向营地 FRET传感器和心房选择腺相关病毒(AAV9)介导的基因治疗将被用于 在特定的细胞微域中解析NDPK-B/C和cAMP的促心律失常作用。这些研究 预计将确定NDPK亚型是否以及如何有助于房颤的发展并作为 验证NDPKs作为预防或治疗房颤的新的可用药靶点的平台。

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.