Mechanistic insight into the role of glycosylation in focal cortical epilepsy through modelling in brain organoids.

An increasing number of neurodevelopmental pathologies are associated with disorders of glycosylation. One such disorder is MOGHE (Mild Malformation of Cortical Development with Oligodendroglial Hyperplasia in Epilepsy), which is primarily caused by brain somatic mutations in the gene SLC35A2. This gene encodes the sole known ER/Golgi UDP-galactose transporter, and mutations in SLC35A2 result in loss of galactose from glycans. The only therapeutic approach to control MOGHE-related seizures is surgical resection of the affected brain region. The host lab has used this tissue to gain insight into the genomic, histological and transcriptomic characteristics of MOGHE. To better understand the pathophysiology of this condition and promote future therapeutic approaches (e.g. galactose supplementation), I will model MOGHE by generating mosaic SLC35A2 knockout myelinating organoids. Through imaging and electrophysiological approaches, I will use these organoids to understand the development of the phenotypic characteristics of MOGHE: oligodendroglial hyperplasia, hypo-myelination, defective neuronal migration, and altered neuronal electrical activity. To better understand the mechanisms underpinning these phenotypes, I will use high-throughput approaches, including single-cell RNA sequencing and glycoproteomics to identify candidate conveyors. Findings from these experiments can then be validated on patient tissues available in the host laboratory. Beyond therapeutic perspectives, the mosaic nature of this model provides an unprecedented opportunity to gain insight into the cell autonomous and non-cell autonomous roles of glycans in cortical development and function. This project incorporates the state of the art in techniques used to study brain development and glycobiology and thus will expand on my existing skills as a researcher in a highly collaborative and open host environment and help me reach my goal of becoming an independent researcher.