Comprehensive transcriptomic and proteomic profiling of mTOR-related epilepsy

Abstract

Malformations of cortical development (MCDs) are a major cause of drug-resistant epilepsy (DRE) in children. A subset of MCDs, including focal cortical dysplasia type II, tuberous sclerosis complex, and hemimegalencephaly, shares characteristic histopathological features and somatic mutations in genes within the PI3K-AKT-mTOR signaling cascade, and is termed mTORopathies. However, the molecular mechanisms that drive epileptogenesis and consequent uncontrollable seizures in these disorders remain poorly understood. Here, we performed integrated genomic, transcriptomic, and proteomic analyses of 60 surgical brain specimens from 42 patients with MCDs and 18 with mesial temporal lobe epilepsy. Targeted genomic sequencing identified 19 somatic mutations in PI3K-AKT-mTOR pathway genes, including novel variants in AKT3 (L51H) and MTOR (A512T). RNA sequencing comparing mTORopathy brains with controls, along with cross-validation using an independent public dataset, identified 287 consistently differentially expressed genes that were consistently altered. Downregulated genes were enriched in oxidative phosphorylation (OXPHOS) and mitochondrial metabolic pathways, whereas upregulated genes were associated with gliogenesis and cellular senescence. Proteomic profiling identified 44 differentially expressed proteins, including significant reductions in OXPHOS-related proteins (COX5B, NDUFS4, GOT2, RAB27B, and DKK3). Our study provides a patient-matched, multi-omics dataset of human mTOR-related epilepsies from a single-institution cohort. Integrated analyses across transcriptomic and proteomic layers highlight impairment of OXPHOS as a molecular hallmark of mTORopathies, Integrated transcriptomic and proteomic analyses identified impaired OXPHOS as a molecular hallmark, potentially contributing to focal hypometabolism in mTORopathy. These findings offer mechanistic insights into epileptogenesis and provide a valuable resource for understanding molecular pathologies and developing mechanism-based therapies for mTOR-related epilepsy.