Mutant prion protein enhances NMDA receptor activity, activates PKC, and triggers rapid excitotoxicity in mice.

Abstract

Neuronal hyperexcitability precedes synapse loss in certain neurodegenerative diseases, yet the synaptic membrane interactions and downstream signaling events remain unclear. The disordered amino terminus of the prion protein (PrPC) has been implicated in aberrant signaling in prion and Alzheimer's disease. To disrupt neuronal interactions and signaling linked to the amino terminus, here we CRISPR-engineered a knock-in mouse expressing mutant PrPC (G92N), generating an N-linked glycosylation site between two functional motifs. Mice developed seizures and necrosis of hippocampal pyramidal neurons, similar to prion-infected mice and consistent with excitotoxicity. Phosphoproteomics revealed phosphorylated glutamate receptors and calcium-sensitive kinases, including protein kinase C (PKC). Additionally, 92N-PrPC-expressing neurons show persistent calcium influx as well as dendritic beading, which was rescued by an NMDA receptor antagonist. Finally, survival of Prnp92N mice was prolonged by blocking active NMDA receptor channels. We propose dysregulated PrPC - NMDA receptor - induced signaling can trigger excitatory - inhibitory imbalance, spongiform degeneration, and neurotoxicity, and that calcium dysregulation is central to PrPC-linked neurodegeneration.