The Regulatory Effect Of Protein Disulfide Isomerase On Platelet GPIbα Ectodomain Shedding

Objective:This study was aimed to investigate the regulatory effect of protein disulfide isomerase on platelet GPIbα ectodomain shedding.Methods: The washed platelets were obtained from healthy volunteers. Platelets were incubated with PDI inhibitor before stimulation with PMA(Phorbol-12-myristate-13-acetate), Dibucaine and collagen. The N-terminal domain of GPIbα was detected by Western blot, and GPIbα expression and the intraplatelet ROS levels were measured by flow cytometry.Results:1)Neither GC content nor GPIbα expression was changed after the washed platelets from the healthy donors were incubated only with PDI inhibitor Bacitracin(P>0.05). It is suggested that inhibition of PDI does not affect platelet GPIbα expression and also does not increase the amount of GC.2)The washed platelets were incubated with PDI inhibitor before stimulation with different stimuli, PMA or Dibucaine, and then GPIbα was cleaved and GPIbα expression was decreased more than the controls(P<0.05). As inhibition of PDI does increase the induced GPIbα ectodomein shedding by PMA, Dibucaine or collagen, PDI maybe play a negative role in the induced GPIbα ectodomein shedding.3)The washed platelets were incubated with PDI inhibitor before stimulation with different stimuli, PMA, Dibucaine or collagen, and then ROS levels were elevated more than the controls(P<0.05).Conclusion:It was concluded that PDI participates in the induced GPIbα ectodomein shedding, and the effect of PDI in this process depends on the change of ROS level inside platelets. These results might provide a new point of view for the platelet drug development.