VEGF modulates NMDA receptors activity in cerebellar granule cells through Src-family kinases before synapse formation.

NMDA type glutamate receptors (NMDAR5) are best known for their role in synaptogenesis and synaptic plasticity. Much less is known about their developmental role before neurons form synapses. We report here that VEGF, which promotes migration of granule cells (GC5) during postnatal cerebellar development, enhances NMDAR-mediated currents and Ca²⁺ influx in immature GCs before synapse formation. The VEGF receptor FIki forms a complex with the NMDAR subunits NR1 and NR2B. In response to VEGF, the number of Flkl/NR2B coclusters on the cell surface increases. Stimulation of FIki by VEGF activates Src-family kinases. which increases tyrosine phosphorylation of NR2B. Inhibition of Src-family kinases abolishes the VEGF-dependent NR2B phosphorylation and amplification of NMDAR-mediated currents and Ca²⁺ influx in GC5. These findings identify VEGF as a modulator of NMDAR5 before synapse formation and highlight a link between an activity-independent neurovascular guidance cue (VEGF) and an activity-regulated neurotransmitter receptor (NMDAR). [ABSTRACT FROM AUTHOR]