氧化型 CaMKII（钙/钙调蛋白依赖性蛋白激酶 II）在杜氏肌营养不良症小鼠模型中心律失常中起关键作用。
Oxidized CaMKII (Ca/Calmodulin-Dependent Protein Kinase II) Is Essential for Ventricular Arrhythmia in a Mouse Model of Duchenne Muscular Dystrophy.
机构信息
Department of Molecular Physiology and Biophysics (Q.W., A.P.Q., S.C., J.R., D.Y.C., D.B., N.L., G.W., G.G.R., X.H.T.W.), Department of Medicine (Cardiology) (N.L., X.H.T.W.), Department of Pediatrics (Cardiology) (X.H.T.W.), and Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX. Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C.). Duke University School of Medicine, Durham, NC (D.B.). Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD (M.E.A.).
出版信息
Circ Arrhythm Electrophysiol. 2018 Apr;11(4):e005682. doi: 10.1161/CIRCEP.117.005682.
BACKGROUND
Duchenne muscular dystrophy patients are prone to ventricular arrhythmias, which may be caused by abnormal calcium (Ca) homeostasis and elevated reactive oxygen species. CaMKII (Ca/calmodulin-dependent protein kinase II) is vital for normal Ca homeostasis, but excessive CaMKII activity contributes to abnormal Ca homeostasis and arrhythmias in cardiomyocytes. Reactive oxygen species induce CaMKII to become autonomously active. We hypothesized that genetic inhibition of CaMKII oxidation (ox-CaMKII) in a mouse model of Duchenne muscular dystrophy can alleviate abnormal Ca homeostasis, thus, preventing ventricular arrhythmia. The objective of this study was to test if selective loss of ox-CaMKII affects ventricular arrhythmias in the mouse model of Duchenne muscular dystrophy.
METHODS AND RESULTS
5-(6)-Chloromethyl-2,7-dichlorodihydrofluorescein diacetate staining revealed increased reactive oxygen species production in ventricular myocytes isolated from mice, which coincides with elevated ventricular ox-CaMKII demonstrated by Western blotting. Genetic inhibition of ox-CaMKII by knockin replacement of the regulatory domain methionines with valines (MM-VV [CaMKII M281/282V]) prevented ventricular tachycardia in mice. Confocal calcium imaging of ventricular myocytes isolated from :MM-VV mice revealed normalization of intracellular Ca release events compared with cardiomyocytes from mice. Abnormal action potentials assessed by optical mapping in mice were also alleviated by genetic inhibition of ox-CaMKII. Knockout of the NADPH oxidase regulatory subunit p47 normalized elevated ox-CaMKII, repaired intracellular Ca homeostasis, and rescued inducible ventricular arrhythmias in mice.
CONCLUSIONS
Inhibition of reactive oxygen species or ox-CaMKII protects against proarrhythmic intracellular Ca handling and prevents ventricular arrhythmia in a mouse model of Duchenne muscular dystrophy.
背景
杜氏肌营养不良症患者易发生室性心律失常，这可能是由于钙（Ca）稳态异常和活性氧（ROS）升高所致。CaMKII（Ca/钙调蛋白依赖性蛋白激酶 II）对于正常的 Ca 稳态至关重要，但过度的 CaMKII 活性会导致心肌细胞的 Ca 稳态异常和心律失常。ROS 诱导 CaMKII 自主激活。我们假设在杜氏肌营养不良症的小鼠模型中，CaMKII 氧化（ox-CaMKII）的遗传抑制可以减轻异常的 Ca 稳态，从而预防室性心律失常。本研究的目的是检测杜氏肌营养不良症小鼠模型中选择性丧失 ox-CaMKII 是否会影响室性心律失常。
方法和结果
5-（6）-氯甲基-2,7-二氯二氢荧光素二乙酸酯染色显示，从 小鼠分离的心室肌细胞中活性氧的产生增加，这与 Western blot 显示的升高的心室 ox-CaMKII 一致。通过将调节域蛋氨酸替换为缬氨酸的基因敲入（MM-VV[CaMKII M281/282V]）抑制 ox-CaMKII 的遗传抑制可预防 小鼠的室性心动过速。与来自 小鼠的心肌细胞相比，从 ：MM-VV 小鼠分离的心室肌细胞的共聚焦钙成像显示细胞内 Ca 释放事件正常化。光学映射评估的异常动作电位在 小鼠中也通过 ox-CaMKII 的遗传抑制得到缓解。NADPH 氧化酶调节亚基 p47 的敲除使升高的 ox-CaMKII 正常化，修复了细胞内 Ca 稳态，并挽救了 小鼠的可诱导性室性心律失常。
结论
抑制活性氧或 ox-CaMKII 可防止促心律失常性细胞内 Ca 处理，并预防杜氏肌营养不良症小鼠模型中的室性心律失常。
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