Oxidized CaMKII in Atrial Fibrillation

描述（由申请人提供）：我们的小组通过CaMK II调节结构域中成对Met残基（281/282）的氧化确定了CaMK II活化的机制，并发现血管紧张素II（Ang II）输注导致心肌Met 281/282氧化，将氧化的CaMK II（ox-CaMK II）锁定为持续活性构型。我们最近发现，与对照组相比，AF患者心房中ox-CaMKII的表达增加，这使我们开发并验证了Ang II输注和增强AF易感性的小鼠模型，以测试ROS和ox-CaMKII在AF中的潜在作用。我们发现，患有起搏诱导的阵发性AF的Ang II输注小鼠和具有血管紧张素转换酶和自发性AF的基因靶向心肌表达的小鼠，与AF患者相似，显示心房ox-CaMKII增加。我们的建议将测试新的假设，ox-CaMKII是一个关键的，但以前未被认识到，信号传导机制，用于驱动promammic事件，有利于AF使用以下特定的目标。1.确定是否增加ox-CaMKII是必要的促血管生成作用的血管紧张素II对AF。实验计划的目标将映射假设的'上游'元素，我们提出的途径，并测量NADPH氧化酶，MsrA活性和CaMKII蛋氨酸氧化对ox-CaMKII水平和AF诱导的贡献。2.确定ox-CaMKII是否有利于房颤的发生。在这一目标的研究将测试的分子和细胞机制“下游"ox-CaMKII，我们假设解释增加AF诱导ox-CaMKII通过增加SR Ca 2+的摄取和释放，向内INCX和延迟后去极化（DAD）。3.确定ox-CaMKII是否通过心房扩大和纤维化促进AF底物。这些实验将确定过量的ox-CaMKII是否通过促进基质金属蛋白酶的表达（有利于心房扩大）、转化生长因子b1和心房肌细胞死亡（诱导反应性和修复性心房纤维化）而有助于促发性心房重构。

DESCRIPTION (provided by applicant): Our group identified a mechanism for CaMKII activation by oxidation of paired Met residues (281/282) in the CaMKII regulatory domain, and found that angiotensin II (Ang II) infusion leads to myocardial Met 281/282 oxidation, locking oxidized CaMKII (ox- CaMKII) into a persistently active configuration. We recently found that expression of ox- CaMKII is increased in atria from AF patients compared to controls, leading us to develop and validate a mouse model of Ang II infusion and enhanced AF susceptibility to test the potential role of ROS and ox-CaMKII in AF. We found that Ang II-infused mice with pacing-induced paroxysmal AF and mice with gene targeted myocardial expression of angiotensin converting enzyme and spontaneous AF, resembled AF patients by showing increased atrial ox-CaMKII. Our proposal will test the novel hypothesis that ox-CaMKII is a critical, but previously unrecognized, signaling mechanism for driving proarrhythmic events that favor AF using the following specific aims. 1. Determine if increased ox-CaMKII is necessary for proarrhythmic effects of Ang II on AF. Experiments planned in the aim will map the hypothesized 'upstream' elements of our proposed pathway and measure the contribution of NADPH oxidase, MsrA activity and CaMKII Met oxidation on ox-CaMKII levels and AF induction. 2. Determine if ox-CaMKII favors AF initiation. Studies in this aim will test a molecular and cellular mechanism 'downstream' to ox-CaMKII that we hypothesize explains increased AF induction by ox-CaMKII through increased SR Ca2+ uptake and release, inward INCX and delayed afterdepolarizations (DADs). 3. Determine if ox-CaMKII contributes to AF substrate through atrial enlargement and fibrosis. These experiments will determine if excessive ox-CaMKII contributes to proarrhythmic atrial remodeling by promoting expression of matrix metalloproteinase (favoring atrial enlargement), transforming growth factor b1 and atrial myocyte death (inducing reactive and reparative atrial fibrosis).