Encoding the Nervous System : DNA Methylation Dynamics in GRIN2B of Human Induced Neural Progenitor Cells

Neurodevelopment is a regulated process involving neural progenitor proliferation, neurogenesis, synaptogenesis, and myelination, all of which are sensitive to epigenetic factors. DNA methylation is a key epigenetic mechanism that regulates gene expression during neurodevelopment and may affect neuronal differentiation and maturation. The glutamate ionotropic receptor NDMA type subunit 2B gene (GRIN2B) encodes a subunit of the NMDA receptor. This subunit plays a key role in synaptic plasticity, neuronal growth, and survival. Mutations of GRIN2B have been linked to multiple neurological and psychiatric disorders. This study aimed to improve the understanding of GRIN2B locus DNA methylation dynamics on differentiating human induced neural progenitor cells (hiNPCs). hiPSCs were differentiated into hiNPCs through dual SMAD inhibition, resulting in three-dimensional hiNPC spheres, mixed neuron-glia brainspheres, and spheres undergone longer network formation and maturation. DNA methylation levels at 4 different CpG sites within the GRIN2B gene were quantified across six developmental time points using pyrosequencing. Significant differences in methylation were observed at CpG sites 1 and 2, particularly during later stages of network formation and maturation, while sites 3 and 4 remained more stable. Varying mean DNA methylation levels of the CpGs across different timepoints may reflect differential, site-specific regulation of NR2B subunit expression in hiNPCs. Building upon previous findings showing decreased DNA methylation correlated with increased levels of mRNA expression in female rats, may suggest the relevance between methylation differences and hiNPC development. This relevance may help to chart the correlation between DNA methylation and neurodevelopmental disorders.