Local RyR2 Control

乙醇（ETOH）具有心脏毒性作用，急性ETOH暴露可导致心肌病， 死亡急性ETOH可导致心律不齐和房颤（AF）。三分之一的新发房颤 例与ETOH中毒有关（1）。在临床上，AF急性消耗大量的 ETOH（暴饮暴食）是假日心脏综合征（HHS）的基础，意外的AF发作。从逻辑上讲，ETOH 禁欲可降低房颤风险，但禁欲失败率较高，因此房颤复发率较高。 常见于ETOH滥用者。考虑到临床因素，打破急性ETOH → AF联系将是有益的。 口头禅“AF引发AF”（即反复AF发作进展为持续性AF）（2）。没有治疗方法 预防或治疗急性ETOH驱动的AF的策略（除了禁欲）。 关于急性ETOH暴露与AF之间的分子机制尚不清楚。我们组最近 发现急性ETOH通过激活应激激活的c-Jun N-末端激酶（JNK）诱发AF（3）。的 激活的JNK然后磷酸化Ca 2 + /钙调蛋白依赖性蛋白激酶II（CaMKII）， 磷酸化心脏ryanodine受体（RyR 2），增加RyR 2的开放概率（Po）。这 信号级联最终促进舒张期RyR 2介导的自发细胞内Ca释放事件 （火花/波）引发AF（3）。我们小组最近还发现，卡维地洛，一种FDA批准的β- 肾上腺素能阻滞剂，对RyR 2开放有直接作用（4），这限制了自发性舒张Ca 引起儿茶酚胺能多态性室性心动过速（CPVT）的波， 心律不齐有趣的是，CPVT和急性ETOH驱动的AF发生在结构正常的心脏中， 共同的病理生理学起源，异常自发RyR介导的舒张期Ca释放。设法 因此，限制这些自发事件具有广泛的治疗前景，而最初开发的药物 CPVT也可能有助于预防/治疗急性ETOH驱动的AF。将检验以下假设。急性 ETOH暴露通过作用于RyR 2-CamKII-JNK 2蛋白逐渐改变舒张期RyR 2功能 驻留在肌浆网（SR）膜上的复合物和新的非阻断性卡维地洛 衍生物可以使急性ETOH驱动的RyR 2功能障碍正常化。将采用多学科方法 为了验证这一假设，我们提出了以下具体目标。1)定义连接JNK的分子机制 激活和单一RyR 2功能。2)测试RyR靶向干预方案，以限制异常 急性ETOH暴露和基础HHS引起的自发舒张期SR Ca释放。培训计划： 申请人将掌握单离子通道记录、结合分析和细胞内Ca ~（2+） 显像申请人将在当地，国家和国际论坛上展示她的研究，她的培训将采取 地点在拉什大学医学中心的生理学和生物物理学系的监督下， 教授兼主席迈克尔·菲尔博士

Ethanol (ETOH) has cardio toxic actions and acute ETOH exposure can lead to cardiomyopathy and death. Acute ETOH can result in irregular heart rhythms and atrial fibrillation (AF). A third of all new-onset AF cases are related to ETOH intoxication (1). In clinics, AF following acute consumption of high amounts of ETOH (binge drinking) underlies Holiday Heart Syndrome (HHS), unexpected AF onset. Logically, ETOH abstinence will reduce AF risk but the failure rate of abstinence is high and consequently AF recurrence is common in ETOH abusers. Breaking the acute ETOH → AF link would be beneficial considering the clinical mantra “AF begets AF” (i.e. repeated AF bouts progress to persistent AF) (2). There are no therapeutic strategies (besides abstinence) that prevent or treat acute ETOH-driven AF. One obstacle is that few details about the molecular mechanisms linking acute ETOH exposure and AF are unknown. Our group recently discovered acute ETOH evokes AF by activating the stress-activated c-Jun N-terminal kinase (JNK) (3). The activated JNK then phosphorylates Ca2+ /calmodulin-dependent protein kinase II (CaMKII) which in turn phosphorylates the cardiac ryanodine receptor (RyR2), increasing the RyR2’s open probability (Po). This signaling cascade ultimately promotes diastolic RyR2-mediated spontaneous intracellular Ca release events (sparks/waves) that initiate AF (3). Our group also recently found that Carvedilol, an FDA-approved β- adrenergic blocker, has a direct action on RyR2 openings (4) and this limits the spontaneous diastolic Ca waves that cause Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), a deadly ventricular arrhythmia. Interestingly, CPVT and acute ETOH-driven AF occur in structurally normal hearts and have a common pathophysiological origin, abnormal spontaneous RyR-mediated diastolic Ca release. Finding ways to limit these spontaneous events thus has broad therapeutic promise and agents originally developed to address CPVT may also help prevent/treat acute ETOH-driven AF. The following hypothesis will be tested. Acute ETOH exposure incrementally alters diastolic RyR2 function by acting on RyR2-CamKII-JNK2 protein complex resident on the sarcoplasmic reticulum (SR) membrane and novel non- 𝛽 blocking Carvedilol derivatives can normalize acute ETOH-driven RyR2 dysfunction. A multidisciplinary approach will be used to test this hypothesis by addressing the following specific aims. 1) Define molecular mechanism(s) linking JNK activation and single RyR2 function. 2) Test RyR-targeted intervention options to limit the abnormal spontaneous diastolic SR Ca release caused by acute ETOH exposure and underlying HHS. Training Plan: The applicant will master the techniques of single ion channel recordings, binding assays and intracellular Ca imaging. Applicant will present her research at local, national and international forums and her training will take place at Rush University Medical Center in the department of Physiology and Biophysics under the supervision of Professor and Chairman, Dr. Michael Fill.