CRMP2 INVOLVEMENT IN P2Y1 RECEPTOR–DRIVEN INCREASE IN NMDAR‑MEDIATED CA²⁺ ENTRY UNDER NEUROTOXIC CONDITIONS

Distinct brain disorders display different aetiologies and phenotypes yet rely on common pathogenic mechanisms. Two events observed across acute and chronic neurodegenerative conditions are excessive NMDAR activation and elevated extracellular ATP. ATP‑dependent activation of P2Y1R catalyses glutamate‑induced neurodegeneration in rat hippocampus by inducing an increase in axonal NMDAR‑mediated Ca²⁺ entry, leading to calpain‑dependent axonal degeneration (Cell Death Dis. 9:297). CRMP2, a phosphoprotein implicated in several neurodegenerative disorders (Mol. Neurobiol. 43:180), regulates the trafficking/activity of GluN2B‑containing NMDARs (J. Biol. Chem. 289:7470), and its phosphorylation is required for glutamate (NMDAR)‑induced axonal degeneration (J. Neurochem. 111:870). We now found in rat hippocampal neurons (DIV14) that Aβ₁₋₄₂ (1 µM; 1–24 h) likewise increased NMDAR‑mediated Ca²⁺ entry. This effect in axons was prevented by the selective P2Y1R antagonist MRS2500 (1 µM) and by CRMP2 knockdown. In vivo, a single i.c.v. injection of Aβ₁₋₄₂ (2–4 nmol) induced synaptic loss and increased CRMP2 phosphorylation (S522, T514, T555) in the cortex; neither effect was observed with continuous i.c.v. administration of MRS2500 (~1 nmol/day). In HEK293T cells, in the absence of CRMP2, P2Y1R activation did not alter GluN2A/GluN1 or GluN2B/GluN1 current density, whereas in CRMP2‑overexpressing cells, P2Y1R activation increased the density of both GluN2A/GluN1 and GluN2B/GluN1 currents. Co-immunoprecipitation assays showed a physical interaction between CRMP2 and GluN2A and GluN2B, but not GluN1. These findings suggest that P2Y1R increases NMDAR-current density in neurotoxic conditions through the regulation of CRMP2.
Funded by NIRG-15-361884 and COMPETE2030-FEDER-00661600