CaMKII modulates sodium current in neurons from epileptic Scn2a mutant mice

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Abstract

Monogenic epilepsies with wide-ranging clinical severity have been associated with mutations in voltage-gated sodium channel genes. In the Scn2aQ54 mouse model of epilepsy, a focal epilepsy phenotype is caused by transgenic expression of an engineered NaV1.2 mutation displaying enhanced persistent sodium current. Seizure frequency and other phenotypic features in Scn2aQ54 mice depend on genetic background. We investigated the neurophysiological and molecular correlates of strain-dependent epilepsy severity in this model. Scn2aQ54 mice on the C57BL/6J background (B6.Q54) exhibit a mild disorder, whereas animals intercrossed with SJL/J mice (F1.Q54) have a severe phenotype. Whole-cell recording revealed that hippocampal pyramidal neurons from B6.Q54 and F1.Q54 animals exhibit spontaneous action potentials, but F1.Q54 neurons exhibited higher firing frequency and greater evoked activity compared with B6.Q54 neurons. These findings correlated with larger persistent sodium current and depolarized inactivation in neurons from F1.Q54 animals. Because calcium/calmodulin protein kinase II (CaMKII) is known to modify persistent current and channel inactivation in the heart, we investigated CaMKII as a plausible modulator of neuronal sodium channels. CaMKII activity in hippocampal protein lysates exhibited a strain-dependence in Scn2aQ54 mice with higher activity in F1.Q54 animals. Heterologously expressed NaV1.2 channels exposed to activated CaMKII had enhanced persistent current and depolarized channel inactivation resembling the properties of F1.Q54 neuronal sodium channels. By contrast, inhibition of CaMKII attenuated persistent current, evoked a hyperpolarized channel inactivation, and suppressed neuronal excitability. We conclude that CaMKII-mediated modulation of neuronal sodium current impacts neuronal excitability in Scn2aQ54 mice and may represent a therapeutic target for the treatment of epilepsy.

Original languageEnglish (US)
Pages (from-to)1696-1701
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number7
DOIs
StatePublished - Feb 14 2017

Fingerprint

Calcium-Calmodulin-Dependent Protein Kinases
Protein Kinases
Sodium
Epilepsy
Neurons
Sodium Channels
Voltage-Gated Sodium Channels
Phenotype
Calcium-Calmodulin-Dependent Protein Kinase Type 2
Mutation
Partial Epilepsy
Pyramidal Cells
Patch-Clamp Techniques
Inbred C57BL Mouse
Action Potentials
Seizures
Genes
Proteins

Keywords

  • CaMKII
  • Epilepsy
  • Voltage-gated sodium channel

ASJC Scopus subject areas

  • General

Cite this

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title = "CaMKII modulates sodium current in neurons from epileptic Scn2a mutant mice",
abstract = "Monogenic epilepsies with wide-ranging clinical severity have been associated with mutations in voltage-gated sodium channel genes. In the Scn2aQ54 mouse model of epilepsy, a focal epilepsy phenotype is caused by transgenic expression of an engineered NaV1.2 mutation displaying enhanced persistent sodium current. Seizure frequency and other phenotypic features in Scn2aQ54 mice depend on genetic background. We investigated the neurophysiological and molecular correlates of strain-dependent epilepsy severity in this model. Scn2aQ54 mice on the C57BL/6J background (B6.Q54) exhibit a mild disorder, whereas animals intercrossed with SJL/J mice (F1.Q54) have a severe phenotype. Whole-cell recording revealed that hippocampal pyramidal neurons from B6.Q54 and F1.Q54 animals exhibit spontaneous action potentials, but F1.Q54 neurons exhibited higher firing frequency and greater evoked activity compared with B6.Q54 neurons. These findings correlated with larger persistent sodium current and depolarized inactivation in neurons from F1.Q54 animals. Because calcium/calmodulin protein kinase II (CaMKII) is known to modify persistent current and channel inactivation in the heart, we investigated CaMKII as a plausible modulator of neuronal sodium channels. CaMKII activity in hippocampal protein lysates exhibited a strain-dependence in Scn2aQ54 mice with higher activity in F1.Q54 animals. Heterologously expressed NaV1.2 channels exposed to activated CaMKII had enhanced persistent current and depolarized channel inactivation resembling the properties of F1.Q54 neuronal sodium channels. By contrast, inhibition of CaMKII attenuated persistent current, evoked a hyperpolarized channel inactivation, and suppressed neuronal excitability. We conclude that CaMKII-mediated modulation of neuronal sodium current impacts neuronal excitability in Scn2aQ54 mice and may represent a therapeutic target for the treatment of epilepsy.",
keywords = "CaMKII, Epilepsy, Voltage-gated sodium channel",
author = "Thompson, {Christopher Hal} and Hawkins, {Nicole Alise} and Kearney, {Jennifer A} and {George Jr}, {Alfred L}",
year = "2017",
month = "2",
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doi = "10.1073/pnas.1615774114",
language = "English (US)",
volume = "114",
pages = "1696--1701",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
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TY - JOUR

T1 - CaMKII modulates sodium current in neurons from epileptic Scn2a mutant mice

AU - Thompson, Christopher Hal

AU - Hawkins, Nicole Alise

AU - Kearney, Jennifer A

AU - George Jr, Alfred L

PY - 2017/2/14

Y1 - 2017/2/14

N2 - Monogenic epilepsies with wide-ranging clinical severity have been associated with mutations in voltage-gated sodium channel genes. In the Scn2aQ54 mouse model of epilepsy, a focal epilepsy phenotype is caused by transgenic expression of an engineered NaV1.2 mutation displaying enhanced persistent sodium current. Seizure frequency and other phenotypic features in Scn2aQ54 mice depend on genetic background. We investigated the neurophysiological and molecular correlates of strain-dependent epilepsy severity in this model. Scn2aQ54 mice on the C57BL/6J background (B6.Q54) exhibit a mild disorder, whereas animals intercrossed with SJL/J mice (F1.Q54) have a severe phenotype. Whole-cell recording revealed that hippocampal pyramidal neurons from B6.Q54 and F1.Q54 animals exhibit spontaneous action potentials, but F1.Q54 neurons exhibited higher firing frequency and greater evoked activity compared with B6.Q54 neurons. These findings correlated with larger persistent sodium current and depolarized inactivation in neurons from F1.Q54 animals. Because calcium/calmodulin protein kinase II (CaMKII) is known to modify persistent current and channel inactivation in the heart, we investigated CaMKII as a plausible modulator of neuronal sodium channels. CaMKII activity in hippocampal protein lysates exhibited a strain-dependence in Scn2aQ54 mice with higher activity in F1.Q54 animals. Heterologously expressed NaV1.2 channels exposed to activated CaMKII had enhanced persistent current and depolarized channel inactivation resembling the properties of F1.Q54 neuronal sodium channels. By contrast, inhibition of CaMKII attenuated persistent current, evoked a hyperpolarized channel inactivation, and suppressed neuronal excitability. We conclude that CaMKII-mediated modulation of neuronal sodium current impacts neuronal excitability in Scn2aQ54 mice and may represent a therapeutic target for the treatment of epilepsy.

AB - Monogenic epilepsies with wide-ranging clinical severity have been associated with mutations in voltage-gated sodium channel genes. In the Scn2aQ54 mouse model of epilepsy, a focal epilepsy phenotype is caused by transgenic expression of an engineered NaV1.2 mutation displaying enhanced persistent sodium current. Seizure frequency and other phenotypic features in Scn2aQ54 mice depend on genetic background. We investigated the neurophysiological and molecular correlates of strain-dependent epilepsy severity in this model. Scn2aQ54 mice on the C57BL/6J background (B6.Q54) exhibit a mild disorder, whereas animals intercrossed with SJL/J mice (F1.Q54) have a severe phenotype. Whole-cell recording revealed that hippocampal pyramidal neurons from B6.Q54 and F1.Q54 animals exhibit spontaneous action potentials, but F1.Q54 neurons exhibited higher firing frequency and greater evoked activity compared with B6.Q54 neurons. These findings correlated with larger persistent sodium current and depolarized inactivation in neurons from F1.Q54 animals. Because calcium/calmodulin protein kinase II (CaMKII) is known to modify persistent current and channel inactivation in the heart, we investigated CaMKII as a plausible modulator of neuronal sodium channels. CaMKII activity in hippocampal protein lysates exhibited a strain-dependence in Scn2aQ54 mice with higher activity in F1.Q54 animals. Heterologously expressed NaV1.2 channels exposed to activated CaMKII had enhanced persistent current and depolarized channel inactivation resembling the properties of F1.Q54 neuronal sodium channels. By contrast, inhibition of CaMKII attenuated persistent current, evoked a hyperpolarized channel inactivation, and suppressed neuronal excitability. We conclude that CaMKII-mediated modulation of neuronal sodium current impacts neuronal excitability in Scn2aQ54 mice and may represent a therapeutic target for the treatment of epilepsy.

KW - CaMKII

KW - Epilepsy

KW - Voltage-gated sodium channel

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U2 - 10.1073/pnas.1615774114

DO - 10.1073/pnas.1615774114

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