PROTEOMIC PROFILING AND IDENTIFICATION OF COFILIN RESPONDING TO OXIDATIVE STRESS IN VASCULAR SMOOTH MUSCLE

We used 2-DE and MALDI-TOF/TOF to identify proteins of vascular smooth muscle cells whose expression was or was not altered by exposure to 500 μM H 2 O 2 for 30 min. We detected more than 800 proteins on silver-stained gels of whole protein extracts from rat aortic smooth muscle strips. Of these proteins, 135 dearly unaffected and 19 having levels altered by exposure to H 2 O 2 were identified. Protein characterization revealed that the most prominent vascular smooth muscle proteins were those with antioxidant, cytoskeletal structure, or muscle contraction. In addition, cofilin, an isoform of the actin depolymerizing factor family, shifted to its basic site on the 2-DE gel as a result of H 2 O 2 treatment. In Western blot analysis of proteins from A7r5 aortic smooth muscle cells, the phosphorylation, but not the expression, of cofilin was decreased by H 2 O 2 in a dose-dependent manner. The H 2 O 2 -induced dephosphorylation of cofilin and apoptosis was inhibited by Na 3 VO 4 , an inhibitor of protein tyrosine phosphatase (PTP). These results suggest that cofilin is one of the proteins regulated by H 2 O 2 treatment in vascular smooth muscle, and has an important role in the induction of vascular apoptosis through PTP-dependent mechanisms.