Time-limited alterations in cortical activity of a knock-in mouse model of KCNQ2-related developmental and epileptic encephalopathy
Time-limited alterations in cortical activity of a knock-in mouse model of KCNQ2-related developmental and epileptic encephalopathy
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DOI：
10.1113/jp282536
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发表时间：
2022-04-27
影响因子：
5.5
通讯作者：
Aniksztejn, Laurent
中科院分区：
文献类型：
--
作者：
Biba-Maazou, Najoua;Becq, Helene;Aniksztejn, Laurent
编码电压门控钾通道Kv 7/M的Kv7.2亚基的KCNQ 2基因中的从头错义变体是新生儿发病的发育性和癫痫性脑病的主要原因。虽然癫痫发作通常在发育过程中消退，但认知/运动缺陷持续存在。为了更好地了解网络功能障碍的细胞机制及其随时间的进展，我们在体内使用自由移动动物的局部场电位记录进行了研究，并在运动皮层切片的II/III和V层中使用膜片钳记录进行了离体研究，来自携带Kv7.2 p.T274M致病性变体的杂合敲入小鼠模型的锥体细胞在新生儿期间的电生理特性，断奶后和幼年发育阶段。我们发现，基因敲入小鼠显示自发性癫痫发作优先在断奶后，而不是在少年阶段。在细胞水平上，该变体导致M电流密度/电导降低和神经元过度兴奋。这些变化观察到在新生儿期在锥体细胞层II/III和断奶后阶段在锥体细胞层V。此外，有一个自发的网络驱动的事件介导的GABA受体的频率增加，这表明中间神经元的兴奋性也增加。然而，所有这些变化不再观察到在层II/III和V的幼年小鼠。因此，我们的数据表明，该变体的作用是受发育调节的。这提出了一种可能性，即在KCNQ 2相关发育性和癫痫性脑病患者中观察到的年龄相关性癫痫缓解是由Kv 7通道活性和神经元兴奋性的时间限制性改变引起的。关键点与发育和癫痫性脑病相关的KCNQ 2基因（Kv7.2亚基中的p.T274M变体）的致病性c.821C>T突变的电生理影响已在体内和离体在新生儿、断奶后和幼年期发育期间敲入小鼠模型的运动皮质切片的II/III和V层中进行了分析。M电流密度和电导下降，第II/III层锥体细胞的兴奋性增加，在切片从新生儿和断奶后敲入小鼠，但不是从青少年敲入小鼠。M电流和第V层锥体细胞的兴奋性在敲入小鼠中仅在断奶后阶段受到影响。自发GABA能网络驱动的事件可以记录，直到断奶后阶段，其频率增加，在层II/III的敲入小鼠。敲入小鼠显示自发性癫痫发作优先在断奶后，而不是在少年阶段。
De novo missense variants in the KCNQ2 gene encoding the Kv7.2 subunit of voltage-gated potassium Kv7/M channels are the main cause of developmental and epileptic encephalopathy with neonatal onset. Although seizures usually resolve during development, cognitive/motor deficits persist. To gain a better understanding of the cellular mechanisms underlying network dysfunction and their progression over time, we investigated in vivo, using local field potential recordings of freely moving animals, and ex vivo in layers II/III and V of motor cortical slices, using patch-clamp recordings, the electrophysiological properties of pyramidal cells from a heterozygous knock-in mouse model carrying the Kv7.2 p.T274M pathogenic variant during neonatal, postweaning and juvenile developmental stages. We found that knock-in mice displayed spontaneous seizures preferentially at postweaning rather than at juvenile stages. At the cellular level, the variant led to a reduction in M current density/conductance and to neuronal hyperexcitability. These alterations were observed during the neonatal period in pyramidal cells of layers II/III and during the postweaning stage in pyramidal cells of layer V. Moreover, there was an increase in the frequency of spontaneous network-driven events mediated by GABA receptors, suggesting that the excitability of interneurons was also increased. However, all these alterations were no longer observed in layers II/III and V of juvenile mice. Thus, our data indicate that the action of the variant is regulated developmentally. This raises the possibility that the age-related seizure remission observed in KCNQ2-related developmental and epileptic encephalopathy patients results from a time-limited alteration of Kv7 channel activity and neuronal excitability. Key points The electrophysiological impact of the pathogenic c.821C>T mutation of the KCNQ2 gene (p.T274M variant in Kv7.2 subunit) related to developmental and epileptic encephalopathy has been analysed both in vivo and ex vivo in layers II/III and V of motor cortical slices from a knock-in mouse model during development at neonatal, postweaning and juvenile stages. M current density and conductance are decreased and the excitability of layer II/III pyramidal cells is increased in slices from neonatal and postweaning knock-in mice but not from juvenile knock-in mice. M current and excitability of layer V pyramidal cells are impacted in knock-in mice only at the postweaning stage. Spontaneous GABAergic network-driven events can be recorded until the postweaning stage, and their frequency is increased in layers II/III of the knock-in mice. Knock-in mice display spontaneous seizures preferentially at postweaning rather than at juvenile stages.