Ca2+-activated KCa3.1 potassium channels contribute to the slow afterhyperpolarization in L5 neocortical pyramidal neurons
Ca2+-activated KCa3.1 potassium channels contribute to the slow afterhyperpolarization in L5 neocortical pyramidal neurons
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DOI：
10.1038/s41598-020-71415-x
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发表时间：
2020-09-02
影响因子：
4.6
通讯作者：
Nikitin, E. S.
中科院分区：
文献类型：
--
作者：
Roshchin, M., V;Ierusalimsky, V. N.;Nikitin, E. S.
已知第 5 层新皮质锥体神经元在尖峰爆发后表现出缓慢的 Ca2+ 依赖性超极化 (sAHP)，这与 CA1 海马细胞中的 sAHP 相似。然而，人们对新皮质中 sAHP 的机制仍知之甚少。在这里，我们确定 Ca2+ 门控钾 KCa3.1 通道是 ER81 阳性新皮质锥体神经元中 sAHP 的贡献者。此外，我们的实验强烈表明，反馈机制中 sAHP 和 KCa3.1 通道之间的关系是第 5 层锥体神经元尖峰频率适应的基础。我们使用几种并行方法证明了 KCa3.1 通道和 sAHP 之间的关系：电生理学、药理学、免疫组织化学和光激活探针。我们的实验表明，第 5 层中的 ER81 免疫荧光与体细胞中的 KCa3.1 免疫荧光共定位。靶向 Ca2+ 解笼锁证实了 KCa3.1 通道的两个主要特征：优先体细胞树突定位和 Ca2+ 驱动的门控。此外，sAHP 和缓慢的 Ca2+ 诱导的超极化电流都对 TRAM-34（一种 KCa3.1 通道的选择性阻断剂）敏感。
Layer 5 neocortical pyramidal neurons are known to display slow Ca2+-dependent after hyperpolarization (sAHP) after bursts of spikes, which is similar to the sAHP in CA1 hippocampal cells. However, the mechanisms of sAHP in the neocortex remain poorly understood. Here, we identified the Ca2+-gated potassium KCa3.1 channels as contributors to sAHP in ER81-positive neocortical pyramidal neurons. Moreover, our experiments strongly suggest that the relationship between sAHP and KCa3.1 channels in a feedback mechanism underlies the adaptation of the spiking frequency of layer 5 pyramidal neurons. We demonstrated the relationship between KCa3.1 channels and sAHP using several parallel methods: electrophysiology, pharmacology, immunohistochemistry, and photoactivatable probes. Our experiments demonstrated that ER81 immunofluorescence in layer 5 co-localized with KCa3.1 immunofluorescence in the soma. Targeted Ca2+ uncaging confirmed two major features of KCa3.1 channels: preferential somatodendritic localization and Ca2+-driven gating. In addition, both the sAHP and the slow Ca2+-induced hyperpolarizing current were sensitive to TRAM-34, a selective blocker of KCa3.1 channels.