Excitatory neurons and astrocytes-specific dysregulation and aberrant interactions are vulnerable to FCDI as suggested by single-cell spatial transcriptomics.

BACKGROUND

Focal cortical dysplasia (FCD) is a common neurodevelopmental disorder characterised by cortical malformations and is a major cause of drug-resistant epilepsy. FCD type I (FCDI) presents with architectural abnormalities of the neocortex but without cytological abnormalities. Currently, FCDI remains a significant clinical challenge.

METHODS

Epileptogenic cortical tissues from three FCDI patients and three relatively normal neocortical tissues as controls were analysed using single-nucleus RNA sequencing and spatial transcriptomic for multi-omics integration.

RESULTS

This study constructed a single-cell spatial transcriptomic atlas of the epileptogenic cortex from FCDI patients. Excitatory neurons (ENs) and astrocytes (Ast) exhibited the most prominent alterations in FCDI. Hub genes associated with FCDI were identified in ENs, and a transcription factor (TF)‒hub gene regulatory network was constructed. Notably, CBLN2highEx-1 was identified as being potentially involved in processes related to neuronal hyperexcitability and cortical development in FCDI. Western blot and immunofluorescence assays validated the altered expression of selected key genes and TFs at the protein level. Additionally, Ast exhibited increased heterogeneity, impaired differentiation and a higher proportion of immature Ast in FCDI, with predicted TFs regulating this process. Further analysis revealed aberrant signalling pathways and ligand‒receptor interactions between ENs and Ast in FCDI, with spatial co-localisation patterns that may contribute to disease progression.

CONCLUSIONS

This study highlights the specific dysregulation of ENs and Ast, along with aberrant cellular communication, which may play a critical role in the pathogenesis of FCDI. These findings provide novel insights into the molecular mechanisms underlying FCDI and offer potential therapeutic targets for precision treatment and drug development.