Chronic ethanol up-regulates the synaptic expression of the nuclear translational regulatory protein AIDA-1 in primary hippocampal neurons.
Recent studies have identified synaptic proteins that undergo synapse-to-nucleus translocation in response to neuronal activity that modulate protein synthesis. One such translational regulatory protein of the postsynaptic density (PSD) is AIDA-1d, which binds to PSD-95 via its C-terminus. Activation of synaptic NMDA receptors induces the cleavage of AIDA-1d, and the N-terminus is then shuttled to nuclear Cajal bodies where it plays a role in regulating global protein synthesis. Chronic ethanol exposure has been shown to increase the synaptic clustering of NMDA receptors and PSD-95. Here, we tested the hypothesis that AIDA-1d regulates chronic ethanol-induced increases in synaptic NMDA receptor expression. As reported, we found that AIDA-1 was highly enriched in dendritic spines and co-localized with PSD-95. Acute NMDA treatment increased AIDA-1 colocalization with p80 coilin, a marker of Cajal bodies. Chronic treatment (4 day) of cultures with ethanol (25-100 mM) or with the NMDA receptor antagonist AP-V (50 μM) enhanced the clustering of AIDA-1 at synaptic sites. However, chronic ethanol treatment (50 mM) in the presence of the NMDA receptor agonist NMDA (2.5 μM) prevented this increase. Surprisingly, PSD-95 did not seem to play a role in the synaptic distribution of AIDA-1 as this distribution was not affected by declustering PSD-95 from synapses in response to inhibition of palmitoylation. We found that lentiviral knockdown of AIDA-1d did not affect protein expression levels of NMDA receptor subunits GluN1, GluN1 C2', or GluN2B. The results of this study demonstrate that synaptic AIDA-1 expression is enhanced by chronic ethanol exposure that can be prevented by concurrent stimulation of NMDA receptors. In addition, we found that the association of AIDA-1 with PSD-95 is not required for its localization to the PSD. Moreover, we found that AIDA-1 does not regulate protein expression levels or alternative splicing of the GluN1 subunit of NMDA receptors.
Department of Neurosciences, 67 President Street, Medical University of South Carolina, Charleston, SC 29425, USA.
Patrick J
PJ
Mulholland
Bryen A
BA
Jordan
L Judson
LJ
Chandler
D000818:Animals; D000076122:Disks Large Homolog 4 Protein; D000431:Ethanol / Q000494:pharmacology*; D006624:Hippocampus / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D016194:Receptors, N-Methyl-D-Aspartate; C068921:p80-coilin; D000431:Ethanol; D016202:N-Methylaspartate