Ca2+-calmodulin-dependent protein kinase II represses cardiac transcription of the L-type calcium channel α1C-subunit gene (Cacna1c) by DREAM translocation
Ca2+-calmodulin-dependent protein kinase II represses cardiac transcription of the L-type calcium channel α1C-subunit gene (Cacna1c) by DREAM translocation
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DOI：
10.1113/jphysiol.2010.201400
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发表时间：
2011-06-01
影响因子：
5.5
通讯作者：
Tavi, Pasi
中科院分区：
文献类型：
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作者：
Ronkainen, Jarkko J.;Hanninen, Sandra L.;Tavi, Pasi
非技术摘要在心肌细胞中，细胞内钙 (Ca2+) 浓度 ([Ca2+](i)) 以心率定义的频率波动会引起细胞收缩。在较长的时间尺度上，相同的波动通过激活各种细胞酶来调节特定基因的表达来定义细胞的特性。在本研究中，我们表征了特定的细胞信号传导通路，解释了 [Ca2+](i) 如何调节 L 型钙通道 (LTCC) 的表达。我们发现，[Ca2+](i) 激活的钙调蛋白激酶 II (CaMKII) 激活下游调节元件 (DRE) 结合转录因子 DREAM，从而抑制 LTCC 的表达。通过实验和数学模型，我们证明通过Ca2+-CaMKII-DREAM级联下调LTCC构成了一种生理反馈机制，使心肌细胞能够将通过LTCC的钙侵入调整为CaMKII检测到的细胞内钙量。最近的研究表明，钙-钙调蛋白依赖性蛋白激酶II的活性发生变化 (CaMKII) 通过调节参与兴奋-收缩 (E-C) 耦合的特定基因诱导独特的心肌细胞表型。为了解释 CaMKII 的转录效应，我们确定了一种新的 CaMKII 依赖性途径，用于控制心肌细胞中 L 型钙通道 (LTCC) 的成孔 α 亚基 (Ca(v)1.2) 的表达。我们发现，胞浆 (delta(C)) 或核 (delta(B)) CaMKII 亚型的过表达选择性下调 Ca(v)1.2 的表达。 CaMKII 活性的药理抑制在不到 24 小时内引起 LTCC 电流密度的可测量变化以及心肌细胞钙信号传导的随后变化。 CaMKII 对 α(1C) 亚基基因 (Cacna1c) 启动子的影响通过删除下游调控元件 (DRE) 来消除，该元件结合转录抑制因子 DREAM/calsenilin/KChIP3。对表达 DREAM-GFP（绿色荧光蛋白）的心肌细胞进行成像显示，CaMKII 增强了钙诱导的 DREAM 核转位。因此，CaMKII 增加了 DREAM 与内源性 Cacna1c 基因的 DRE 共有序列的结合。通过数学模型，我们证明通过 Ca2+-CaMKII-DREAM 级联下调 LTCC 构成了一种生理反馈机制，使心肌细胞能够将通过 LTCC 的钙侵入调整为 CaMKII 检测到的细胞内钙量。
Non-technical summaryIn heart muscle cells, fluctuations of intracellular calcium (Ca2+) concentration ([Ca2+](i)) at the frequency defined by the heart rate induce contractions of the cells. Over a longer timescale the same fluctuations define the properties of the cells by regulating expressions of specific genes through the activation of a variety of cellular enzymes. In this study, we have characterized a specific cell signalling pathway, explaining how [Ca2+](i) regulates the expression of the L-type calcium channel (LTCC). We show that [Ca2+](i)-activated calmodulin kinase II (CaMKII) activates downstream regulatory element (DRE) binding transcription factor DREAM, which consequently suppresses the expression of LTCCs. By experiments and mathematical modelling we demonstrate that the LTCC downregulation through the Ca2+-CaMKII-DREAM cascade constitutes a physiological feedback mechanism enabling cardiomyocytes to adjust the calcium intrusion through LTCCs to the amount of intracellular calcium detected by CaMKII.Recent studies have demonstrated that changes in the activity of calcium-calmodulin-dependent protein kinase II (CaMKII) induce a unique cardiomyocyte phenotype through the regulation of specific genes involved in excitation-contraction (E-C)-coupling. To explain the transcriptional effects of CaMKII we identified a novel CaMKII-dependent pathway for controlling the expression of the pore-forming alpha-subunit (Ca(v)1.2) of the L-type calcium channel (LTCC) in cardiac myocytes. We show that overexpression of either cytosolic (delta(C)) or nuclear (delta(B)) CaMKII isoforms selectively downregulate the expression of the Ca(v)1.2. Pharmacological inhibition of CaMKII activity induced measurable changes in LTCC current density and subsequent changes in cardiomyocyte calcium signalling in less than 24 h. The effect of CaMKII on the alpha(1C)-subunit gene (Cacna1c) promoter was abolished by deletion of the downstream regulatory element (DRE), which binds transcriptional repressor DREAM/calsenilin/KChIP3. Imaging DREAM-GFP (green fluorescent protein)-expressing cardiomyocytes showed that CaMKII potentiates the calcium-induced nuclear translocation of DREAM. Thereby CaMKII increases DREAM binding to the DRE consensus sequence of the endogenous Cacna1c gene. By mathematical modelling we demonstrate that the LTCC downregulation through the Ca2+-CaMKII-DREAM cascade constitutes a physiological feedback mechanism enabling cardiomyocytes to adjust the calcium intrusion through LTCCs to the amount of intracellular calcium detected by CaMKII.