AIMS Ankyrin B (AnkB) is an adaptor protein that assembles Na+/K+-ATPase (NKA) and Na+/Ca2+ exchanger (NCX) in the AnkB macromolecular complex. Loss-of-function mutations in AnkB cause the AnkB syndrome in humans, characterized by ventricular arrhythmias and sudden cardiac death. It is unclear to what extent NKA binding to AnkB allows regulation of local Na+ and Ca2+ domains and hence NCX activity. METHODS AND RESULTS To investigate the role of NKA binding to AnkB in cardiomyocytes, we synthesized a disruptor peptide (MAB peptide) and its AnkB binding ability was verified by pulldown experiments. As opposed to control, the correlation between NKA and NCX currents was abolished in adult rat ventricular myocytes dialyzed with MAB peptide, as well as in cardiomyocytes from AnkB+/- mice. Disruption of NKA from AnkB (with MAB peptide) increased NCX-sensed cytosolic Na+ concentration, reduced Ca2+ extrusion through NCX, and increased frequency of Ca2+ sparks and Ca2+ waves without concomitant increase in Ca2+ transient amplitude or SR Ca2+ load, suggesting an effect in local Ca2+ domains. Selective inhibition of the NKAα2 isoform abolished both the correlation between NKA and NCX currents and the increased rate of Ca2+ sparks and waves following NKA/AnkB disruption, suggesting that an AnkB/NKAα2/NCX domain controls Ca2+ fluxes in cardiomyocytes. CONCLUSION NKA binding to AnkB allows ion regulation in a local domain, and acute disruption of the NKA/AnkB interaction using disruptor peptides lead to increased rate of Ca2+ sparks and waves. The functional effects were mediated through the NKAα2 isoform. Disruption of the AnkB/NKA/NCX domain could be an important pathophysiological mechanism in the AnkB syndrome.

中文翻译：

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Na + / K + -ATPase与锚蛋白B的偶联控制了心肌细胞中Na + / Ca2 +交换子的活性。

AIMS锚蛋白B（AnkB）是一种衔接蛋白，可在AnkB大分子复合物中组装Na + / K + -ATPase（NKA）和Na + / Ca2 +交换子（NCX）。AnkB的功能丧失突变会导致人类的AnkB综合征，其特征为室性心律不齐和心源性猝死。尚不清楚NKA与AnkB的结合能在多大程度上调节局部Na +和Ca2 +结构域，从而调节NCX活性。方法和结果为了研究NKA与AnkB结合在心肌细胞中的作用，我们合成了干扰肽（MAB肽），并通过下拉实验验证了其与AnkB的结合能力。与对照相反，在用MAB肽透析的成年大鼠心室心肌细胞以及来自AnkB +/-小鼠的心肌细胞中，NKA和NCX电流之间的相关性被消除。从AnkB（带有MAB肽）中破坏NKA增加了NCX感应的胞质Na +浓度，减少了通过NCX的Ca2 +挤出，并且增加了Ca2 +火花和Ca2 +波的频率，而没有同时增加Ca2 +瞬变幅度或SR Ca2 +负荷，这表明了局部作用Ca2 +域。NKAα2亚型的选择性抑制消除了NKA / NCX电流之间的相关性以及NKA / AnkB破坏后Ca2 +火花和波动的增加率，这表明AnkB /NKAα2/ NCX域控制了心肌细胞中的Ca2 +通量。结论NKA与AnkB结合可以在局部域调节离子，并且使用破坏肽对NKA / AnkB相互作用的急性破坏会导致Ca2 +火花和波动的发生率增加。功能作用通过NKAα2同工型介导。