Gating of long-term depression by Ca2+/calmodulin-dependent protein kinase II through enhanced cGMP signalling in cerebellar Purkinje cells.
Gating of long-term depression by Ca2+/calmodulin-dependent protein kinase II through enhanced cGMP signalling in cerebellar Purkinje cells.
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Ca2/钙调蛋白依赖性蛋白激酶 II 通过增强小脑浦肯野细胞中的 cGMP 信号传导来门控长期抑郁。
DOI：
10.1113/jphysiol.2012.245787
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
T. Hirano
中科院分区：
文献类型：
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作者：
S. Kawaguchi;T. Hirano
要点•小脑浦肯野细胞平行纤维突触的长期抑制（LTD）被认为是运动学习的细胞基础。•虽然Ca2+/钙调蛋白依赖性蛋白激酶II（CaMKII）与LTD诱导和运动学习有关，但其潜在的分子机制仍不清楚。•通过模拟和实验的结合应用，我们试图 探索 CaMKII 参与 LTD 的潜在信号通路。我们的数据显示，CaMKII 支持由其他蛋白激酶（如蛋白激酶 C 和促分裂原激活蛋白激酶）组成的 LTD 诱导信号通路。CaMKII 对 LTD 诱导通路的门控是通过磷酸二酯酶 1 的负调节介导的，从而促进 cGMP/蛋白激酶 G (PKG) 通路。结果，蛋白磷酸酶 2A 活性被抑制，支持 LTD 诱导。•此外，一氧化氮介导的 cGMP/PKG 激活补偿了 LTD 诱导中 CaMKII 激活的缺乏。•这项研究提供了对 LTD 调节的复杂细胞内信号传导机制的全面理解。摘要平行纤维突触的长期抑制 (LTD) 小脑浦肯野细胞被认为是运动学习的细胞基础。尽管 Ca2+/钙调蛋白依赖性蛋白激酶 II (CaMKII) 作为重要的 Ca2+ 传感分子参与 LTD 诱导，但其潜在的信号传导机制仍不清楚。在这里，我们尝试使用系统生物学方法，结合对大鼠培养的浦肯野细胞进行电生理学和 FRET 成像实验的验证，探索 CaMKII 参与 LTD 的潜在信号通路。模型模拟预测以下级联是 CaMKII 对 LTD 贡献的候选机制：CaMKII 负向调节磷酸二酯酶 1 (PDE1)，随后促进 cGMP/蛋白激酶 G (PKG) 信号通路并下调蛋白磷酸酶 2A (PP-2A)，从而支持 LTD 诱导的正反馈循环 由蛋白激酶 C (PKC) 和丝裂原激活蛋白激酶 (MAPK) 的相互激活组成。该模型的建议得到了全细胞膜片钳记录实验的证实。此外，FRET测量细胞内cGMP浓度表明，CaMKII激活导致cGMP持续增加，支持CaMKII诱导LTD的信号机制。此外，我们发现一氧化氮 (NO) 激活 cGMP/PKG 途径可以支持 LTD 诱导，而无需激活 CaMKII。因此，本研究阐明了 NO 和 Ca2+/CaMKII（LTD 所需的两个重要因素）之间的相互作用。
Key points•Long‐term depression (LTD) at parallel fibre synapses on a cerebellar Purkinje cell has been regarded as a cellular basis for motor learning.•Although Ca2+/calmodulin‐dependent protein kinase II (CaMKII) has been implicated in the LTD induction and motor learning, the underlying molecular mechanism remains unclear.•By combined application of simulation and experiments, we have attempted to explore the potential signalling pathway underlying the CaMKII involvement in LTD. Our data show that CaMKII supports the LTD‐inducing signalling pathway consisting of other protein kinases such as protein kinase C and mitogen‐activated protein kinase.•The gating of the LTD‐inducing pathway by CaMKII is mediated by negative regulation of phosphodiesterase 1, and the resultant facilitation of the cGMP/protein kinase G (PKG) pathway. As a result, protein phosphatase 2A activity was suppressed, supporting the LTD induction.•In addition, nitric oxide‐mediated cGMP/PKG activation compensated for the lack of CaMKII activation in LTD induction.•This study provides a comprehensive understanding of elaborate intracellular signalling mechanisms for LTD regulation.AbstractLong‐term depression (LTD) at parallel fibre synapses on a cerebellar Purkinje cell has been regarded as a cellular basis for motor learning. Although Ca2+/calmodulin‐dependent protein kinase II (CaMKII) has been implicated in the LTD induction as an important Ca2+‐sensing molecule, the underlying signalling mechanism remains unclear. Here, we attempted to explore the potential signalling pathway underlying the CaMKII involvement in LTD using a systems biology approach, combined with validation by electrophysiological and FRET imaging experiments on a rat cultured Purkinje cell. Model simulation predicted the following cascade as a candidate mechanism for the CaMKII contribution to LTD: CaMKII negatively regulates phosphodiesterase 1 (PDE1), subsequently facilitates the cGMP/protein kinase G (PKG) signalling pathway and down‐regulates protein phosphatase 2A (PP‐2A), thus supporting the LTD‐inducing positive feedback loop consisting of mutual activation of protein kinase C (PKC) and mitogen‐activated protein kinase (MAPK). This model suggestion was corroborated by whole‐cell patch clamp recording experiments. In addition, FRET measurement of intracellular cGMP concentration revealed that CaMKII activation causes sustained increase of cGMP, supporting the signalling mechanism of LTD induction by CaMKII. Furthermore, we found that activation of the cGMP/PKG pathway by nitric oxide (NO) can support LTD induction without activation of CaMKII. Thus, this study clarified interaction between NO and Ca2+/CaMKII, two important factors required for LTD.