NO-dependent CaMKII activation during β-adrenergic stimulation of cardiac muscle
NO-dependent CaMKII activation during β-adrenergic stimulation of cardiac muscle
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DOI：
10.1093/cvr/cvt201
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发表时间：
2013-12-01
影响因子：
10.8
通讯作者：
Niggli, Ernst
中科院分区：
文献类型：
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作者：
Gutierrez, Daniel A.;Fernandez-Tenorio, Miguel;Niggli, Ernst
在 β-肾上腺素能受体 (-AR) 刺激期间，蛋白激酶对心肌细胞兰尼碱受体的磷酸化可能会导致舒张期 Ca-2 火花频率增加。尽管在 -AR 刺激过程中蛋白激酶 A 会迅速激活，但这似乎更多地依赖于通过尚未确定的信号通路激活 Ca-2/钙调蛋白依赖性蛋白激酶 II (CaMKII)。本研究的目的是确定和表征舒张期单个心肌细胞在 -AR 刺激过程中导致 CaMKII 激活和 Ca-2 火花频率升高的机制。共聚焦成像显示 -AR 刺激增加心肌细胞内源性 NO 的产生，导致 CaMKII 的 NO 依赖性激活，并随后增加舒张期 Ca-2 火花频率。火花频率的这些变化可以通过暴露于 NO 供体 GSNO 来模拟，并且对 CaMKII 抑制剂 KN-93 和 AIP 敏感。在体外，CaMKII 被亚硝化，并且在 GSNO 存在的情况下，其活性保持增加，独立于 Ca-2，正如生化测定所评估的那样。心肌细胞的 AR 刺激可能通过涉及 NO 的新型直接途径激活 CaMKII，而不需要 Ca-2 瞬变。两条已建立的信号通路之间的这种串扰可能会导致肾上腺素能应激期间致心律失常的舒张期 Ca-2 释放和 Ca-2 波，特别是与心脏病结合时。此外，CaMKII 的 NO 依赖性激活可能会对许多细胞信号系统和细胞类型产生影响。
During -adrenergic receptor (-AR) stimulation, phosphorylation of cardiomyocyte ryanodine receptors by protein kinases may contribute to an increased diastolic Ca-2 spark frequency. Regardless of prompt activation of protein kinase A during -AR stimulation, this appears to rely more on activation of Ca-2/calmodulin-dependent protein kinase II (CaMKII), by a not yet identified signalling pathway. The goal of the present study was to identify and characterize the mechanisms which lead to CaMKII activation and elevated Ca-2 spark frequencies during -AR stimulation in single cardiomyocytes in diastolic conditions.Confocal imaging revealed that -AR stimulation increases endogenous NO production in cardiomyocytes, resulting in NO-dependent activation of CaMKII and a subsequent increase in diastolic Ca-2 spark frequency. These changes of spark frequency could be mimicked by exposure to the NO donor GSNO and were sensitive to the CaMKII inhibitors KN-93 and AIP. In vitro, CaMKII became nitrosated and its activity remained increased independent of Ca-2 in the presence of GSNO, as assessed with biochemical assays.-AR stimulation of cardiomyocytes may activate CaMKII by a novel direct pathway involving NO, without requiring Ca-2 transients. This crosstalk between two established signalling pathways may contribute to arrhythmogenic diastolic Ca-2 release and Ca-2 waves during adrenergic stress, particularly in combination with cardiac diseases. In addition, NO-dependent activation of CaMKII is likely to have repercussions in many cellular signalling systems and cell types.