Defining the role of KCNN1 in atrial arrhythmias

定义 KCNN1 在房性心律失常中的作用

• 批准号: 10666164
• 负责人: Dmitry A Terentyev
• 金额: $ 15.75万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10666164
• 关键词: AF2; Action Potentials; Acute; Adrenergic beta-Antagonists; Affect; Animal Model; Anti-Arrhythmia Agents; Arrhythmia; Atrial Fibrillation; Attenuated; Binding; Biosensor; CRISPR/Cas technology; Calcium-Activated Potassium Channel; Calmodulin; Calsequestrin; Cardiac; Cardiac Myocytes; Cells; Chronic; Complex; Data; Disease; Electrophysiology (science); Event; Experimental Models; Genetic; Goals; Heart; Heart Atrium; Homeostasis; Human; Image; Incidence; Individual; Inherited; Inner mitochondrial membrane; Knock-out; Knockout Mice; Knowledge; Link; MLLT2 gene; Maps; Mediating; Membrane Potentials; Mitochondria; Morbidity - disease rate; Mus; Muscle Cells; Optics; Play; Population; Potassium Channel; Production; Protein Isoforms; Proteins; Publishing; Quality of life; Reactive Oxygen Species; Reporting; Role; Ryanodine Receptor Calcium Release Channel; Sarcolemma; Sarcoplasmic Reticulum; Signal Transduction; Stress; Structure; Techniques; Testing; Therapeutic; Tissues; Transgenic Mice; Translating; Transmission Electron Microscopy; Ventricular; Work; channel blockers; experimental study; gain of function; genome wide association study; heart rhythm; improved; lifetime risk; loss of function; mortality; mouse model; novel; overexpression; patch clamp; pharmacologic; reduce symptoms; small hairpin RNA; therapeutic evaluation; treatment strategy; voltage

Atrial fibrillation (AF) is the most prevalent form of cardiac arrhythmia affecting up to 2% of population and with an estimated individual lifetime risk of 25%-30%. AF is associated with a significant reduction in quality of life and increased morbidity and mortality. Frontline therapies such as beta blockers and Ca2+ channels blockers help control cardiac rhythm to reduce the symptoms, but do not prevent AF. Therefore the discovery of atria- specific targets to treat AF is imperative. Recently, small conductance Ca2+ activated K+ (SK) channels have emerged as a plausible atria-specific anti-arrhythmic target, given their limited functional roles in ventricular cardiomyocytes from healthy hearts. All three SK channels isoforms (SK1-3) are expressed both in atria and ventricles. However, the therapeutic potential of SK2 and SK3 remains highly controversial, given both loss- and gain-of-function of these channels were linked to increased atrial arrhythmogenesis in various genetic mouse models and in GWAS association studies. Furthermore, recent reports demonstrated SK current in ventricular myocytes from diseased or stressed hearts, revealed to play a protective role in reducing Ca2+-dependent arrhythmia-triggering events. Importantly, our previously published data showed no discernible role of SK1 (KCNN1) in ventricular protection, unlike SK2 and SK3. Based on this knowledge, and the fact that SK1 is the only isoform with 2-5 fold higher expression in atria vs ventricles, we posit that SK1 can be a bona fide atria- specific antiarrhythmic target, unlike SK2 and SK3. Accordingly, the major goal of this proposal is to establish the roles of SK1 in normal atrial myocytes (AMs) and AMs from the hearts with AF. Abnormally high activity of sarcoplasmic reticulum (SR) Ca2+ release channel complex, the ryanodine receptor (RyR2), is thought to underlie arrhythmia trigger for AF. Therefore, to test SK1 antiarrhythmic potential, we will use the well-established mouse model of RyR2 complex gain-of function caused by calsequestrin (CASQ2) knockout, a SR protein that determines controls RyR2 activity and SR Ca2+ storage capacity. To explore the functional consequences of gain- and loss-of-SK1 channel function, we propose to generate new cardiac-specific SK1 overexpression and KO mouse lines. Importantly, SK1 might be expressed in the mitochondrial inner membrane in addition to the sarcolemma. We hypothesize that facilitating sarcolemmal SK1 channel function may substantially diminish pro- arrhythmic early and delayed afterdepolarizations (EADs and DADs respectively) by countering the depolarizing force of L-type Ca2+ channels and Na+/Ca2+ exchanger, thus reducing triggered activity. We posit that mito-SK1 channel activation can further attenuate pro-arrhythmic Ca2+-dependent DADs and EADs by reducing excessive production of damaging reactive oxygen species, thereby improving disturbed RyR2 complex-mediated SR Ca2+ release in diseased AMs. We anticipate our work will validate SK1 as a novel atria-specific antiarrhythmic target.

心房颤动（AF）是最常见的心律失常形式，影响高达2%的人口， 估计个人终生风险为25%-30%。AF与生活质量显着下降有关 发病率和死亡率增加。一线治疗，如β受体阻滞剂和Ca2+通道阻滞剂 帮助控制心律以减轻症状，但不能预防AF。因此，心房的发现- 治疗AF的具体目标是必要的。最近，小电导Ca~（2+）激活的K~+（SK）通道已被发现， 由于其在心室肌中的功能作用有限， 健康心脏的心肌细胞。所有三种SK通道亚型（SK 1 - 3）在心房和心房肌中表达， 心室然而，SK2和SK3的治疗潜力仍然存在很大争议， 这些通道的功能获得与各种遗传小鼠中心房肌生成的增加有关 模型和GWAS关联研究。此外，最近的报道表明，SK电流在心室肌细胞， 来自患病或应激心脏的心肌细胞，显示在降低Ca2+依赖性 引发疟疾的事件。重要的是，我们先前发表的数据显示SK1没有明显的作用， （KCNN1）在心室保护中，与SK2和SK3不同。基于这一知识，以及SK 1是 只有在心房中表达比心室高2 - 5倍的同种型，我们认为SK 1可以是真正的心房， 特异性抗肿瘤靶点，不像SK2和SK3。因此，本提案的主要目标是建立 SK 1在正常心房肌细胞（AM）和AF心脏AM中的作用。 肌浆网（SR）钙释放通道复合物，兰尼碱受体（RyR2），被认为是 房颤的心律失常触发因素。因此，为了测试SK 1的抗心律失常潜力，我们将使用成熟的小鼠 RyR2复合物功能获得模型由钙螯合蛋白（CASQ2）敲除引起，钙螯合蛋白是一种SR蛋白， 确定控制RyR2活性和SR Ca2+储存能力。为了探索功能性后果， SK1通道功能的获得和丧失，我们建议产生新的心脏特异性SK1过表达， KO鼠标线。重要的是，SK1除了在线粒体膜上表达外，还可能在线粒体内膜上表达。 肌膜我们假设，促进肌膜SK1通道功能可能会大大减少促凋亡蛋白的表达。 通过对抗去极化，产生早期和延迟后去极化（分别为EAD和DAD） L-型Ca~（2+）通道和Na~+/Ca~（2+）交换器的作用力，从而降低触发活性。我们将mito-SK 1 通道激活可通过减少过量的钙离子，进一步减弱促钙离子依赖性DAD和EAD。 产生破坏性活性氧，从而改善受干扰的RyR2复合物介导的SR Ca2 + 在患病的AM中释放。我们预计我们的工作将验证SK 1作为一种新的心房特异性抗心律失常靶点。