Supramolecular aggregation of aquaporin-4 shapes astrocyte collective migration and mechanics.

Aquaporin-4 (AQP4), the main astrocytic water channel, assembles into supramolecular structures known as Orthogonal Arrays of Particles (OAPs). While AQP4-mediated water fluxes are known to influence cytoskeletal dynamics at the single-cell level, their role in collective migration remain unclear. Using primary WT and OAP-deficient (OAP-null) astrocytes, we investigated cell migration under control and proinflammatory conditions. In wound healing assays, control OAP-null astrocytes exhibited greater migratory capacity, while inflamed cells were largely immotile. Particle Image Velocimetry revealed genotype and condition-specific migration patterns, with OAP-null astrocytes displaying more linear trajectories. Cytokine treatment also reduced AQP4 and Connexin-43 expression and impaired gap-junctional communication in both genotypes. Calcein-AM quenching assays showed reduced water permeability in OAP-null cells, independently of treatment. These findings highlight the supramolecular organization of AQP4 as a key determinant of astrocyte collective migration and suggest that chronic inflammation induces a poorly coordinated phenotype through dysregulation of AQP4 and gap-junctional networks.