Scn2a-KO Mouse

Scn2a, encoding the neuronal sodium channel NaV1.2, is crucial for action potential initiation and propagation in developing excitatory cortical neurons. Sodium channels are integral to the normal functioning of the nervous system, and Scn2a's role in this process underscores its biological importance. Genetic models, such as mouse models, are valuable for studying Scn2a's function [2,5].

Pathogenic variants in Scn2a are linked to a spectrum of neurodevelopmental disorders including developmental and epileptic encephalopathies, benign familial neonatal-infantile seizures, episodic ataxia, and autism spectrum disorder with or without intellectual disability [1,2,3,4]. In mouse models, loss-of-function of Scn2a-encoded NaV1.2 sodium channels in granule cells impaired high-frequency transmission to Purkinje cells and long-term potentiation in the cerebellum, leading to hypersensitization of the vestibulo-ocular reflex, which may underlie sensory hypersensitivity in autism spectrum disorder [6]. Also, NaV1.2 loss in mature pyramidal neurons reduced action potential backpropagation into dendrites, impairing synaptic plasticity and strength, providing insights into circuit and behavioral dysfunction in ASD [5].

In conclusion, Scn2a is essential for neuronal function, especially in action potential regulation and synaptic function. Studies using mouse models have revealed its role in various neurodevelopmental disorders, particularly autism spectrum disorder and related sensory and synaptic dysfunctions. Understanding Scn2a's function through these models offers potential insights into the mechanisms of these disorders and may guide the development of therapeutic strategies [5,6].

References:

1. Reynolds, Claire, King, Mary D, Gorman, Kathleen M. 2019. The phenotypic spectrum of SCN2A-related epilepsy. In European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society, 24, 117-122. doi:10.1016/j.ejpn.2019.12.016. https://pubmed.ncbi.nlm.nih.gov/31924505/

2. Sanders, Stephan J, Campbell, Arthur J, Cottrell, Jeffrey R, Spiro, John E, Bender, Kevin J. 2018. Progress in Understanding and Treating SCN2A-Mediated Disorders. In Trends in neurosciences, 41, 442-456. doi:10.1016/j.tins.2018.03.011. https://pubmed.ncbi.nlm.nih.gov/29691040/

3. Hedrich, Ulrike B S, Lauxmann, Stephan, Lerche, Holger. . SCN2A channelopathies: Mechanisms and models. In Epilepsia, 60 Suppl 3, S68-S76. doi:10.1111/epi.14731. https://pubmed.ncbi.nlm.nih.gov/31904120/

4. Wolff, Markus, Brunklaus, Andreas, Zuberi, Sameer M. . Phenotypic spectrum and genetics of SCN2A-related disorders, treatment options, and outcomes in epilepsy and beyond. In Epilepsia, 60 Suppl 3, S59-S67. doi:10.1111/epi.14935. https://pubmed.ncbi.nlm.nih.gov/31904126/

5. Spratt, Perry W E, Ben-Shalom, Roy, Keeshen, Caroline M, Sanders, Stephan J, Bender, Kevin J. 2019. The Autism-Associated Gene Scn2a Contributes to Dendritic Excitability and Synaptic Function in the Prefrontal Cortex. In Neuron, 103, 673-685.e5. doi:10.1016/j.neuron.2019.05.037. https://pubmed.ncbi.nlm.nih.gov/31230762/

6. Wang, Chenyu, Derderian, Kimberly D, Hamada, Elizabeth, Bouvier, Guy, Bender, Kevin J. 2024. Impaired cerebellar plasticity hypersensitizes sensory reflexes in SCN2A-associated ASD. In Neuron, 112, 1444-1455.e5. doi:10.1016/j.neuron.2024.01.029. https://pubmed.ncbi.nlm.nih.gov/38412857/