Prechtel Helena, Hartmann Sven, Minge Daniel, Bähring Robert
Institut für Zelluläre und Integrative Physiologie, Zentrum für Experimentelle Medizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
PLoS One. 2018 Jan 31;13(1):e0191911. doi: 10.1371/journal.pone.0191911. eCollection 2018.
Kv4.2 channels mediate a subthreshold-activating somatodendritic A-type current (ISA) in hippocampal neurons. We examined the role of accessory Kv channel interacting protein (KChIP) binding in somatodendritic surface expression and activity-dependent decrease in the availability of Kv4.2 channels. For this purpose we transfected cultured hippocampal neurons with cDNA coding for Kv4.2 wild-type (wt) or KChIP binding-deficient Kv4.2 mutants. All channels were equipped with an externally accessible hemagglutinin (HA)-tag and an EGFP-tag, which was attached to the C-terminal end. Combined analyses of EGFP self-fluorescence, surface HA immunostaining and patch-clamp recordings demonstrated similar dendritic trafficking and functional surface expression for Kv4.2[wt]HA,EGFP and the KChIP binding-deficient Kv4.2[A14K]HA,EGFP. Coexpression of exogenous KChIP2 augmented the surface expression of Kv4.2[wt]HA,EGFP but not Kv4.2[A14K]HA,EGFP. Notably, activity-dependent decrease in availability was more pronounced in Kv4.2[wt]HA,EGFP + KChIP2 coexpressing than in Kv4.2[A14K]HA,EGFP + KChIP2 coexpressing neurons. Our results do not support the notion that accessory KChIP binding is a prerequisite for dendritic trafficking and functional surface expression of Kv4.2 channels, however, accessory KChIP binding may play a potential role in Kv4.2 modulation during intrinsic plasticity processes.
Kv4.2通道介导海马神经元中阈下激活的树突-胞体A型电流（ISA）。我们研究了辅助性Kv通道相互作用蛋白（KChIP）结合在Kv4.2通道树突-胞体表面表达以及活性依赖的可用性降低中的作用。为此，我们用编码Kv4.2野生型（wt）或KChIP结合缺陷型Kv4.2突变体的cDNA转染培养的海马神经元。所有通道均配备有外部可及的血凝素（HA）标签和附着于C末端的EGFP标签。通过对EGFP自发荧光、表面HA免疫染色和膜片钳记录的联合分析表明，Kv4.2[wt]HA,EGFP和KChIP结合缺陷型Kv4.2[A14K]HA,EGFP具有相似的树突运输和功能性表面表达。外源性KChIP2的共表达增强了Kv4.2[wt]HA,EGFP的表面表达，但没有增强Kv4.2[A14K]HA,EGFP的表面表达。值得注意的是，在共表达Kv4.2[wt]HA,EGFP + KChIP2的神经元中，活性依赖的可用性降低比共表达Kv4.2[A14K]HA,EGFP + KChIP2的神经元中更明显。我们的结果不支持辅助性KChIP结合是Kv4.2通道树突运输和功能性表面表达的先决条件这一观点，然而，辅助性KChIP结合可能在内在可塑性过程中对Kv4.2的调节中发挥潜在作用。
