Postsynaptic density protein-93 (PSD-93) is enriched in the postsynaptic density and is involved in N-methyl-d-aspartate receptor (NMDAR) triggered neurotoxicity through PSD-93/NMDAR/nNOS signaling pathway. In the present study, we found that PSD-93 deficiency reduced infarcted volume and neurological deficits induced by transient middle cerebral artery occlusion (tMCAO) in the mice. To identify novel targets of PSD-93 related neurotoxicity, we applied isobaric tags for relative and absolute quantitative (iTRAQ) labeling and combined this labeling with on-line two-dimensional LC/MS/MS technology to elucidate the changes in protein expression in PSD-93 knockout mice following tMCAO. The proteomic data set consisted of 1892 proteins. Compared to control group, differences in expression levels in ischemic group >1.5-fold and <0.66-fold were considered as differential expression. A total of 104 unique proteins with differential abundance levels were identified, among which 17 proteins were selected for further validation. Gene ontology analysis using UniProt database revealed that these differentially expressed proteins are involved in diverse function such as synaptic transmission, neuronal neurotransmitter and ion transport, modification of organelle membrane components. Moreover, network analysis revealed that the interacting proteins were involved in the transport of synaptic vesicles, the integrity of synaptic membranes and the activation of the ionotropic glutamate receptors NMDAR1 and NMDAR2B. Finally, RT-PCR and Western blot analysis showed that SynGAP, syntaxin-1A, protein kinase C β, and voltage-dependent L-type calcium channels were inhibited by ischemia-reperfusion. Identification of these proteins provides valuable clues to elucidate the mechanisms underlying the actions of PSD-93 in ischemia-reperfusion induced neurotoxicity.
Keywords: Excitotoxicity; Ischemic stroke; PSD-93; Proteomic analysis.
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