Authors :
Presenting Author: Emily Shrimpton, BS – The University of Texas at San Antonio
Mark Kos, PhD – University of Texas Rio Grande Valley
Dianne Cruz, PhD – Duke University
Charles Szabo, MD – UT Health San Antonio
Melanie Carless, PhD – University of Texas San Antonio
Rationale: Genetic generalized epilepsies (GGEs) account for 40% of US cases. For phenotypes that closely resemble human epilepsy, several mouse models have been developed that exhibit GGE-like spike-wave EEG discharges, however the translatability of such models is hindered by differences in neurodevelopment and brain anatomical structure. Thus, generation of a robust preclinical model that can recapitulate human physiological and neuroanatomical structure and function is of high importance. Baboons represent a natural model for GGE and therefore in this study we aim to assess gene and miRNA transcriptional profiles to determine the relevance of baboons as preclinical models of epilepsy.
Methods:
We isolated the medial orbitofrontal cortex (mOFC) from a pilot cohort of four baboons (n=2 epilepsy, n=2 controls) and performed single-nuclei RNA sequencing (Parse Biosciences). Fastq files were aligned to either the human genome (GRCh38) or the baboon genome (Panubis1.0) and differential expression analysis was performed using TrailmakerTM (Parse Biosciences). We are also investigating small-RNA regulation using the PPMS tool in R.
Results:
Preliminary results showed no significant differences in cell type composition amongst cases and controls. Differential gene expression analysis implicated RRP8, a component of the energy-dependent nucleolar silencing complex, to be upregulated in the GABAergic neurons of mOFC in epileptic baboons (log2FC > 1.5). Non-coding RNAs (e.g., MIR1915HG) also showed differential expression between cases and controls. Pathway analysis showed significant enrichment of “Collagen chain trimerization” (FDR=0.016), and Protein-Protein Interaction (PPI) network analysis of the same differentially expressed genes showed significant enrichment of PPI connectivity (P=0.04) in a cluster centered around EGFR as a hub gene (log2FC ~1.3 in epileptic baboons).
Conclusions:
Our pilot study suggests differences in transcriptional regulation between epileptic and control baboons, specifically in the mOFC. Further studies are underway, with increased sample size, to make further determinations on the significant pathways involved and test the feasibility of diagnostic and therapeutic practices (such as miRNA-based interventions - mimics and antagomirs) for this preclinical model for epilepsy.
Funding: NIH (1R56NS135399)