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Time-limited alterations in cortical activity of a Knock-in mice model of KCNQ2- related Developmental and Epileptic Encephalopathy

Abstract : Abstract De novo missense variants in the KCNQ2 gene encoding the Kv7.2 subunit of the voltage-gated potassium Kv7/M channel are the main cause of Developmental and Epileptic Encephalopathy (DEE). KCNQ2 related-DEE is characterized by pharmaco-resistant neonatal seizures associated with a developmental delay. While seizures usually resolve some weeks or months after birth, cognitive/behavioral deficits persist. To better understand the cellular mechanisms underlying KCNQ2-associated 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 (KI) mouse model carrying the p.T274M pathogenic variant during neonatal, post-weaning and juvenile developmental stages. We found that KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. At the cellular level, the variant led to a reduction in M current density/chord conductance and to an increase in neuronal excitability. These alterations were observed already during the neonatal period in pyramidal cells of layers II / III and during post-weaning stage in pyramidal cells of layer V. Moreover there was an increase in the frequency of spontaneous network driven events mediated by GABA receptors in the layers II/III suggesting that the excitability of some interneurons was also increased. However, all these alterations were time limited and no more observed in layers II/III and V of juvenile mice. At this stage, M-current density and neuronal excitability were not different from the measurements made in juvenile wild-type mice. Thus our data indicate that the action of the variant on neuronal activity is developmentally regulated and that some cellular mechanisms leading to the recovery of Kv7/M channels function took place during brain maturation of KI mice. These results raise the possibility that the age related seizure remission observed in KCNQ2 -related DEE patient results also from a time limited alteration of Kv7 channels activity and neuronal excitability.
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Preprints, Working Papers, ...
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https://hal-amu.archives-ouvertes.fr/hal-03630409
Contributor : Valérie Gall Connect in order to contact the contributor
Submitted on : Tuesday, April 5, 2022 - 8:55:49 AM
Last modification on : Thursday, April 7, 2022 - 3:33:40 AM

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Najoua Biba, Hélène Becq, Marie Kurz, Emilie Pallesi, Laurent Villard, et al.. Time-limited alterations in cortical activity of a Knock-in mice model of KCNQ2- related Developmental and Epileptic Encephalopathy. 2022. ⟨hal-03630409⟩

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