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Genetic variants in SCN2A, encoding the NaV1.2 voltage-gated sodium channel, are associated with a range of neurodevelopmental disorders with overlapping phenotypes. Some variants fit into a framework wherein gain-of-function missense variants that increase neuronal excitability lead to developmental and epileptic encephalopathy, while loss-of-function variants that reduce neuronal excitability lead to intellectual disability and/or autism spectrum disorder (ASD) with or without co-morbid seizures. One unique case less easily classified using this framework is the de novo missense variant SCN2A-p.K1422E, associated with infant-onset developmental delay, infantile spasms and features of ASD. Prior structure-function studies demonstrated that K1422E substitution alters ion selectivity of NaV1.2, conferring Ca2+ permeability, lowering overall conductance and conferring resistance to tetrodotoxin (TTX). Based on heterologous expression of K1422E, we developed a compartmental neuron model incorporating variant channels that predicted reductions in peak action potential (AP) speed. We generated Scn2aK1422E mice and characterized effects on neurons and neurological/neurobehavioral phenotypes. Cultured cortical neurons from heterozygous Scn2aK1422E/+ mice exhibited lower current density with a TTX-resistant component and reversal potential consistent with mixed ion permeation. Recordings from Scn2aK1442E/+ cortical slices demonstrated impaired AP initiation and larger Ca2+ transients at the axon initial segment during the rising phase of the AP, suggesting complex effects on channel function. Scn2aK1422E/+ mice exhibited rare spontaneous seizures, interictal electroencephalogram abnormalities, altered induced seizure thresholds, reduced anxiety-like behavior and alterations in olfactory-guided social behavior. Overall, Scn2aK1422E/+ mice present with phenotypes similar yet distinct from other Scn2a models, consistent with complex effects of K1422E on NaV1.2 channel function.

Additional file 1: Figure S1. Representative adipose tissue images. Representative histological images in (A) subcutaneous, (B) retroperitoneal, and (C) mesenteric white adipose tissue. Control and PCOS rats were treated with and without empagliflozin (EMPA). Images were taken at 40× magnification. Figure S2. Effect of EMPA on protein expression on antioxidant enzymes in retroperitoneal white adipose tissue in PCOS. Effect of EMPA on retroperitoneal white adipose tissue (WAT) protein expression of (A) cytosolic superoxide dismutase (SOD1, ~ 18 kDa), (B) mitochondrial superoxide dismutase (SOD2, ~ 22 kDa), and (C) catalase (~ 60 kDa) after 3 weeks of EMPA treatment. Data were normalized by total protein content (TPC). Data are expressed as mean ± SEM and were analyzed by two-way ANOVA followed by Tukey post hoc tests. No significant interaction was observed by two-way ANOVA. n = 4–5 per group. Figure S3. Effect of EMPA on protein expression on antioxidant enzymes in mesenteric white adipose tissue in PCOS. Effect of EMPA on mesenteric white adipose tissue (WAT) protein expression of (A) cytosolic superoxide dismutase (SOD1, ~ 18 kDa), (B) mitochondrial superoxide dismutase (SOD2, ~ 22 kDa), and (C) catalase (~ 60 kDa) after 3 weeks of EMPA treatment. Data were normalized by total protein content (TPC). Data are expressed as mean ± SEM and were analyzed by two-way ANOVA followed by Tukey post hoc tests. No significant interaction was observed by two-way ANOVA. n = 4 per group.