Vitamin D-Binding Protein Acts in the Actin Scavenge System and Can Have Increased Expression During Aspirin Therapy

While the clinical efficacy of aspirin in cerebral thrombosis prevention has been well established, its mechanism of action is still controversial. In an effort to better understand these mechanisms and to identify potential biomarkers, comparative proteomic analysis between 18 patients both pre-aspirin treatment at the time of cerebral thrombotic onset (control group) and post-aspirin treatment (experiment group) was carried out using two-dimensional gel electrophoresis (2-DE) in combination with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDITOF/ MS). Of the 228 2-DE identified differentially expressed protein spots, 11 proteins showed more than a 1.5-fold difference. Of these, vitamin D-binding protein (DBP) and actin were further examined via Western blot and showed consistent results, with DBP levels significantly increased post-aspirin treatment (114.04 ± 16.69) relative to pre-treatment (66.33 ± 5.61) while actin showed the opposite trend (p < 0.01 for both comparisons). Next, co-immunoprecipitation analysis of DBP and actin showed direct binding. Furthermore, a protein-protein interaction network of DBP and the other differentially expressed proteins was constructed using Ingenuity Pathway Analysis software. These results suggest that DBP acts in the actin scavenge system and consequently the increase in DBP levels correlated with aspirin therapy in cerebral thrombotic patients. These findings also suggest that aspirin may prevent platelet aggregation and thrombosis through the actions of DBP and other DBP related proteins.