Genetic deletion of NP1 prevents hypoxic-ischemic neuronal death via reducing AMPA receptor synaptic localization in hippocampal neurons.

Trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (ampars) to excitatory synapses is critical to their synaptic functions. previously,we have shown induction of neuronal pentraxin 1 (np1) and its colocalization with ampar subunit glur1 in hypoxic-ischemic (hi) brain injury. however,the role of np1 in mediating glur1 surface expression,trafficking,and clustering at synapses in hi neuronal death is unclear. primary hippocampal neurons,isolated from wild-type (wt) and np1-knockout (c57bl/6 background) mice at div 12 to 14 were exposed to 2 to 8 hours of oxygen glucose deprivation (ogd)-in vitro conditions that mimic human stroke. ogd exposure resulted in time-dependent induction of np1 (∼4-fold),enhanced redistribution of amap glur1 receptors at excitatory synapses,and increased neuronal death. we observed a significant increase in surface and synaptic glur1 clusters that colocalized with psd-95 on dendrites with a simultaneous decrease in internalized glur1. surface cross-linking with bs(3) showed enhanced membrane insertions of glur1,and increased phosphorylation at ser-845 further supported enhanced surface availability of glur1 after ogd. np1 protein colocalized with glur1 and psd-95,and ogd significantly increased their synaptic coclustering. most strikingly,the genetic deletion of np1 resulted in decreases in surface glur1 cluster density,synaptic localization,phospho-glur1 (ser-845) levels,and neuronal death after ogd compared with wt neurons. ampa (50 μmol/l) induced np1 and significant cell death in wt but not in np1-/- neurons. our results indicate that np1 plays a key role in synaptic clustering of glur1,suggesting that targeting np1 might be a practical approach to preventing ischemic brain damage.