Single cell RNA-seq transriptomic analysis of epileptogenesis in mice with a genetic Nav1.2 channelopathy

Birgit Engeland1 , Malte Stockebrand1, Vladislava Milchevskaya2, Peter Nürnberg3, Achim Tresch2, Dirk Isbrandt1

1 DZNE and University of Cologne
2 University Hospital Cologne
3 University of Cologne

Voltage-gated sodium channels are essential for action potential initiation in neurons. Mutations in the SCN2A gene encoding NaV1.2 are associated with a broad spectrum of epilepsies, ranging from benign phenotypes to severe epileptic encephalopathy.

Recently, a missense mutation in SCN2A (p.A263V) was identified in a patient with neonatal onset, therapy-resistant seizures and variable episodes of ataxia, myoclonus, headache and back pain, starting at the age of 18 months.

To investigate the underlying mechanisms of epileptogenesis, we inserted this gain-of-function mutation in the mouse Nav1.2-encoding gene Scn2a.

Homozygous and heterozygous mice, but not their wild-type littermates displayed electrographic seizures already at P6/7. Because of this early seizure phenotype and strong Nav1.2 expression between P5 and P15 in CA1 and CA3 regions of the hippocampus, we performed single-cell (sc)RNA-Seq experiments using dorsal CA3 tissue from P7 wild-type and A263V knock-in mice.

We identified heterogeneous hippocampal cell populations. Cell type-specific differential gene expression between genotypes revealed distinct and common transcriptomic alterations associated with epileptogenesis.

Further analyses may help discerning pathological, maladaptive changes from compensatory or protective adaptations and support the identification of novel targets for genetic and eventually pharmacological antiepileptic treatment strategies.