Phosphoryaltion levels of ERK5 in acute myocardial infarction patients and its role in platelet activation in vitro / 复旦学报（医学版）

ABSTRACT

Objective To observe the phosphorylation levels of extracellular signal-regulated kinase 5 (ERK5) in acute myocardial infarction (AMI) patients and the effects of ERK5 selective inhibitor XMD8-92 on human platelet activation in vitro,and to explore its mechanism.Methods Western blot was applied to detect the phosphorylation levels of ERK5,Akt473 and Akt308 in AMI patients (n =34) and stable angina patients (n =33,control).The effects of different concentration of XMD8-92 on human platelet aggregation induced by collagen was tested by aggregometer in vitro.The release of ATP was measured simultaneously by luciferase detection.The effects of XMD8-92 on integrin aIIbβ3 were detected by platelet spreading on immobilized fibrinogen and clot retraction.The effects of XMD8-92 on phosphorylation levels of Akt473,Akt308 PTEN370 and ERK5 were detected by Western blot.Results The levels of phosphor-Akt473,Akt308 and phosphor-ERK5 were significantly higher in AMI patients than that in control group (P＜0.05).ERK5 inhibitor XMD8-92 diminished collagen-induced platelet aggregation,ATP secretion,the average area of platelet spreading on immobilized fibrinogen and the clot retraction extent.The levels of phosphor-Akt (Ser-473/Thr-308) and phosphor-PTEN (Ser370) were significantly down-regulated in the presence of XMD8-92.Conclusions ERK5 plays a role in platelet activation in AMI process.It regulates platelet activation by regulating PTEN and Akt phosphorylation.Its specific inhibitor is hoped to be new antithrombotic drug.