SHAPING CORTICAL INTERNEURON MIGRATION THROUGH MECHANICAL SIGNALING DURING BRAIN DEVELOPMENT

Cortical interneurons (cINs) are generated in the ganglionic eminences (GE) and migrate tangentially to populate the developing cortex. During migration, cINs encounter mechanical forces arising from cell–cell interactions and the extracellular matrix, yet how mechanotransduction influences their behavior remains poorly understood. Here we aim to investigate how mechanotransduction events shape cINs behaviour during cortical development. By combining atomic force microscopy (AFM) with time-lapse imaging, we found that the cortical intermediate zone becomes stiffer at embryonic day (E)16.5 compared to E13.5, correlating with reduced migratory speed and decreased nuclear translocation frequency of cINs. Using heterochronic organotypic slice cultures, we showed that E16.5 cINs migrating within a younger (E13.5) cortical environment exhibit increased speed and nuclear translocation frequency compared to age-matched controls. Similar stage-dependent differences were observed when E13.5 and E16.5 cINs were cultured in a viscous 3D matrix. Single-cell AFM measurements revealed that E16.5 cINs display softer somas and increased nuclear deformation during migration. Consistently, transcriptomic and proteomic data from cINs at both stages indicated differences in expression of key nuclear and mechanotransduction factors during development. Together, our findings suggest that while migrating, E16.5 cINs might be more sensitive to environmental changes in part due to their own viscoelastic properties which would allow them to integrate shifts of substrate stiffness and adapt their migratory behavior. Ongoing single-cell multiomics analyses of migrating cINs cultured in hydrogels of increasing stiffness will further elucidate molecular mechanisms linking mechanical cues to cIN maturation and identity.