Comparative gain-of-function effects of the KCNMA1-N999S mutation on human BK channel properties
Comparative gain-of-function effects of the KCNMA1-N999S mutation on human BK channel properties
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DOI：
10.1152/jn.00626.2019
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发表时间：
2020-02-01
影响因子：
2.5
通讯作者：
Meredith, Andrea L.
中科院分区：
文献类型：
--
作者：
Moldenhauer, Hans J.;Matychak, Katia K.;Meredith, Andrea L.
KCNMA1编码电压和钙激活的钾通道，在脑生理学中起着关键作用。KCNMA1基因突变与癫痫和/或运动障碍(PNK1)有关。与这些表型相关的两个KCNMA1突变，D434G和N999S，先前被发现对BK通道活动产生功能增益(GOF)效应。据报道，有三名新患者携带N999S病毒。其中一个携带第二个突变R1128W，但这些突变在生理K+条件下的影响尚未报道，也未与D434G进行比较。在这项研究中，我们研究了新的N999S/R1128W双突变N999S和D434G在脑BK通道剪接变异体中的特征，比较了生理K+梯度和动作电位电压指令对BK电流特性的影响。在HEK293T细胞中表达了N999S、N999S/R1128W和D434G基因，并进行了膜片钳电生理研究。N999S BK电流负移，与野生型(WI)和4340相比，激活快，失活慢。与单独突变N999S相比，双突变N999S/R1128W没有表现出任何额外的电流特性变化。评估了抗癫痫药物乙酰唑胺对WT和N999S通道的直接调节能力。WT和N999S通道对抗癫痫药物乙酰唑胺均不敏感，但对抑制剂帕西林均敏感。我们的结论是，N999S是一个强GOF突变，超过了D434G表型，不受R1128W的抑制。乙酰唑胺对WT或N999S通道没有直接调制作用，这表明它可能不适用于携带GOF KCNMA1突变的患者。新发现和值得注意的KCNMA1连锁通道病是一种新的神经疾病，其特征是BK电压和钙激活钾通道的突变。癫痫和运动障碍相关的功能获得突变N999S和D434G构成了队列中最多的患者数量。本研究首次对D434G和N999S BK通道特性以及来自另一患者的新的双突变N999S/R1128W进行了比较，确定了动作电位刺激期间的功能效应。
KCNMA1, encoding the voltage- and calcium-activated potassium channel, has a pivotal role in brain physiology. Mutations in KCNMA1 are associated with epilepsy and/or dyskinesia (PNK1)3). Two KCNMA1 mutations correlated with these phenotypes, D434G and N999S, were previously identified as producing gain-of-function (GOF) effects on BK channel activity. Three new patients have been reported harboring N999S. one carrying a second mutation, R1128W, but the effects of these mutations have not yet been reported under physiological K + conditions or compared to D434G. In this study, we characterize N999S, the novel N999S/R1128W double mutation, and D434G in a brain BK channel splice variant, comparing the effects on BK current properties under a physiological K+ gradient with action potential voltage commands. N999S, N999S/R1128W, and D434G cDNAs were expressed in HEK293T cells and characterized by patch-clamp electrophysiology. N999S BK currents were shifted to negative potentials, with faster activation and slower deactivation compared with wild type (WI) and 1)4340. The double mutation N999S/R1128W did not show any additional changes in current properties compared with N999S alone. The antiepileptic drug acetazolamide was assessed for its ability to directly modulate WT and N999S channels. Neither the WT nor N999S channels were sensitive to the antiepileptic drug acetazolamide, but both were sensitive to the inhibitor paxilline. We conclude that N999S is a strong GOF mutation that surpasses the D434G phenotype, without mitigation by R1128W. Acetazolamide has no direct modulatory action on either WT or N999S channels, indicating that its use may not be contraindicated in patients harboring GOF KCNMA1 mutations.NEW & NOTEWORTHY KCNMA1 -linked channelopathy is a new neurological disorder characterized by mutations in the BK voltageand calcium-activated potassium channel. The epilepsy- and dyskinesia-associated gain-of-function mutations N999S and D434G comprise the largest number of patients in the cohort. This study provides the first direct comparison between D434G and N999S BK channel properties as well as a novel double mutation, N999S/R1128W, from another patient, defining the functional effects during an action potential stimulus.