Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism

Developmental and epileptic encephalopathies (DEEs), a class of devastating neurological disorders characterized by recurrent seizures and exacerbated by disruptions to excitatory/inhibitory balance in the brain, are commonly caused by mutations in ion channels. Disruption of, or variants in, FGF13...

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Main Authors: Susan Lin, Aravind R Gade, Hong-Gang Wang, James E Niemeyer, Allison Galante, Isabella DiStefano, Patrick Towers, Jorge Nunez, Maiko Matsui, Theodore H Schwartz, Anjali Rajadhyaksha, Geoffrey S Pitt
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Language:English
Published: eLife Sciences Publications Ltd 2025-01-01
Series:eLife
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Online Access:https://elifesciences.org/articles/98661
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author Susan Lin
Aravind R Gade
Hong-Gang Wang
James E Niemeyer
Allison Galante
Isabella DiStefano
Patrick Towers
Jorge Nunez
Maiko Matsui
Theodore H Schwartz
Anjali Rajadhyaksha
Geoffrey S Pitt
author_facet Susan Lin
Aravind R Gade
Hong-Gang Wang
James E Niemeyer
Allison Galante
Isabella DiStefano
Patrick Towers
Jorge Nunez
Maiko Matsui
Theodore H Schwartz
Anjali Rajadhyaksha
Geoffrey S Pitt
author_sort Susan Lin
collection DOAJ
description Developmental and epileptic encephalopathies (DEEs), a class of devastating neurological disorders characterized by recurrent seizures and exacerbated by disruptions to excitatory/inhibitory balance in the brain, are commonly caused by mutations in ion channels. Disruption of, or variants in, FGF13 were implicated as causal for a set of DEEs, but the underlying mechanisms were clouded because FGF13 is expressed in both excitatory and inhibitory neurons, FGF13 undergoes extensive alternative splicing producing multiple isoforms with distinct functions, and the overall roles of FGF13 in neurons are incompletely cataloged. To overcome these challenges, we generated a set of novel cell-type-specific conditional knockout mice. Interneuron-targeted deletion of Fgf13 led to perinatal mortality associated with extensive seizures and impaired the hippocampal inhibitory/excitatory balance while excitatory neuron-targeted deletion of Fgf13 caused no detectable seizures and no survival deficits. While best studied as a voltage-gated sodium channel (Nav) regulator, we observed no effect of Fgf13 ablation in interneurons on Navs but rather a marked reduction in K+ channel currents. Re-expressing different Fgf13 splice isoforms could partially rescue deficits in interneuron excitability and restore K+ channel current amplitude. These results enhance our understanding of the molecular mechanisms that drive the pathogenesis of Fgf13-related seizures and expand our understanding of FGF13 functions in different neuron subsets.
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spelling doaj-art-c203d883eca346739222aa0f6d7675a42025-01-08T15:27:59ZengeLife Sciences Publications LtdeLife2050-084X2025-01-011310.7554/eLife.98661Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanismSusan Lin0https://orcid.org/0000-0001-9344-6594Aravind R Gade1Hong-Gang Wang2James E Niemeyer3Allison Galante4Isabella DiStefano5Patrick Towers6Jorge Nunez7Maiko Matsui8https://orcid.org/0000-0001-9706-8244Theodore H Schwartz9Anjali Rajadhyaksha10Geoffrey S Pitt11https://orcid.org/0000-0003-2246-0289Cardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesDepartment of Neurological Surgery and Brain and Mind Research Institute, Weill Cornell Medicine of Cornell University, New York Presbyterian Hospital, New York, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesDepartment of Neurological Surgery and Brain and Mind Research Institute, Weill Cornell Medicine of Cornell University, New York Presbyterian Hospital, New York, United StatesDepartment of Pediatrics, Division of Pediatric Neurology, Weill Cornell Medicine, New York City, United States; Brain and Mind Research Institute, Weill Cornell Medicine, New York, United StatesCardiovascular Research Institute, Weill Cornell Medicine, New York City, United StatesDevelopmental and epileptic encephalopathies (DEEs), a class of devastating neurological disorders characterized by recurrent seizures and exacerbated by disruptions to excitatory/inhibitory balance in the brain, are commonly caused by mutations in ion channels. Disruption of, or variants in, FGF13 were implicated as causal for a set of DEEs, but the underlying mechanisms were clouded because FGF13 is expressed in both excitatory and inhibitory neurons, FGF13 undergoes extensive alternative splicing producing multiple isoforms with distinct functions, and the overall roles of FGF13 in neurons are incompletely cataloged. To overcome these challenges, we generated a set of novel cell-type-specific conditional knockout mice. Interneuron-targeted deletion of Fgf13 led to perinatal mortality associated with extensive seizures and impaired the hippocampal inhibitory/excitatory balance while excitatory neuron-targeted deletion of Fgf13 caused no detectable seizures and no survival deficits. While best studied as a voltage-gated sodium channel (Nav) regulator, we observed no effect of Fgf13 ablation in interneurons on Navs but rather a marked reduction in K+ channel currents. Re-expressing different Fgf13 splice isoforms could partially rescue deficits in interneuron excitability and restore K+ channel current amplitude. These results enhance our understanding of the molecular mechanisms that drive the pathogenesis of Fgf13-related seizures and expand our understanding of FGF13 functions in different neuron subsets.https://elifesciences.org/articles/98661sodium channelsepilepsyinhibitory interneuron
spellingShingle Susan Lin
Aravind R Gade
Hong-Gang Wang
James E Niemeyer
Allison Galante
Isabella DiStefano
Patrick Towers
Jorge Nunez
Maiko Matsui
Theodore H Schwartz
Anjali Rajadhyaksha
Geoffrey S Pitt
Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
eLife
sodium channels
epilepsy
inhibitory interneuron
title Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
title_full Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
title_fullStr Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
title_full_unstemmed Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
title_short Interneuron FGF13 regulates seizure susceptibility via a sodium channel-independent mechanism
title_sort interneuron fgf13 regulates seizure susceptibility via a sodium channel independent mechanism
topic sodium channels
epilepsy
inhibitory interneuron
url https://elifesciences.org/articles/98661
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