Objective: To explore the impact of Rac1 activation on the proliferation and migration under the stimulation of PDGF-BB (platelet derived growth factor-BB).
Methods: The inhibitory effects of Rac1 inhibitor (NSC23766) and Rac1siRNA on the proliferation and migration of vascular smooth muscle cell under the stimulation of PDGF-BB were measured by CCK8 assay and Transwell chamber. The time characteristics of Rac1 activity and pi-JNK expression under the stimulation of PDGF-BB was detected by GST pulldown assay and Western blot. And the inhibitory effects of NSC23766 and Rac1siRNA on the Rac1 activation and pi-JNK expression were also measured.
Results: Migration and proliferation of vascular smooth muscle cell increased significantly after the stimulation of PDGF-BB (50 µg/L). Migration and proliferation was inhibited significantly after a pretreatment of Rac1siRNA and various concentrations of NSC23766 (25, 50, 100 µg/L). After the stimulation of PDGF-BB, the expression of pi-JNK and Rac1 activity increased over time. Rac1-GTP peaked at 5 minutes and pi-JNK at 15 minute. The expressions of pi-JNK at 15 minutes and Rac1-GTP at 5 minutes were inhibited significantly by Rac1siRNA and NSC23766 in a concentration-dependent manner.
Conclusion: JNK phosphorylation is controlled by Rac1 activation. And Rac1 activation play a pivotal role in the migration and proliferation of aortic smooth muscle cell under the stimulation of PDGF-BB.