Abstracts

Rationale: Dravet Syndrome (DS) is a catastrophic, epileptic encephalopathy predominantly caused by de novo mutations in the SCN1A gene that encodes the voltage-gated sodium channel subunit α1. DS is characterized by early-life febrile seizures, spontaneous pharmaco-resistant seizures, intellectual disability, psychomotor dysfunction, and a high mortality rate due to sudden unexpected death in epilepsy (SUDEP). Although the exact mechanism of SUDEP is unclear, post-ictal apnea that causes respiratory distress and precedes asystole has been recognized as an important pathomechanism. The hindbrain (HB) is a master regulator of breathing, heart rate, and vasomotor control. Repeated seizure spread to the HB can impair energy metabolism which can subsequently alter respiratory/cardiac functions. Previous studies in DS mice revealed age-dependent changes in the HB metabolome and alveolar structural integrity. In the current study, we asked if there are transcriptomic changes in the HB and lungs of DS mice. Transcriptomic profiling will help unravel changes in different cell types and signaling pathways that might offer key insights into the molecular mechanisms that cause SUDEP.

Methods: Dravet Syndrome HET mice (Scn1a^A1783V/WT; Sox-Cre C57Bl/6J) (males and females) exhibit a high mortality rate (~50% through P60) potentially due to increased susceptibility to SUDEP. Perfused HB, and lung samples were collected from age-matched (PND40-60) wildtype (WT) and HET mice and submitted for transcriptomic profiling (single-nuclei (HB), single-cell (lungs); High-throughput Genomics (HTG) Core Facility; University of Utah).

Results: Single-nuclei RNA sequencing of HET HB showed significant downregulation (log (pval) = 1e-25 vs WT) of pathways associated with mitochondrial oxidative phosphorylation, ribosomal biogenesis, and protein translation. Oligodendrocyte cell clusters appeared to be distinctly different in HETs compared to WTs. Single-cell RNA sequencing of HET lung tissue showed significant upregulation (log (pval) = 1e-25 vs WT) of pathways involved in ribosomal biogenesis, natural killer (NK) cell-mediated inflammatory response, and oxidative phosphorylation. NK, and fibroblast cell clusters appeared to be altered in HETs compared to WTs.


Conclusions: Initial transcriptomic profiling of HET HB and lung has revealed disruptions in pathways linked to protein translation, energy metabolism, and inflammatory responses. These findings suggest that transcriptome-level changes in the HB and lung might potentially contribute to SUDEP in DS mice.

Funding: Dravet Syndrome Foundation