J Thro Hae：prohibitins可作为心血管疾病药物研发新靶点

Y. Zhang1,†, Y. Wang1,2,†, Y. Xiang1, W. Lee1, Y. Zhang1

Keywords: platelets;prohibitin;thrombin;PAR1 Summary Background: Prohibitins (PHBs), comprising the two homologous members PHB1 and PHB2, are ubiquitously expressed and highly conserved. The membrane PHBs are reported to be involved in typhoid fever, obesity and cancer metastasis. Proteomic studies have revealed the presence of PHBs in human platelets, but the roles of PHBs during platelet aggregation are unknown. Objectives: The present study aimed to investigate the role of PHBs in platelet aggregation. Methods and results: PHB1 and PHB2 were detected on the surface of human platelets using flow cytometry and confocal microscopy. The PHBs were distributed in lipid rafts, as determined by sucrose density centrifugation. In addition, the PHBs were associated with protease-activated receptor 1 (PAR1), as determined by Bm-TFF2 (a PAR1 agonist)-affinity chromatography, co-immunoprecipitation and confocal microscopy. The platelet aggregation, αIIbβ3 activation, granular secretion and calcium mobilization stimulated by low concentrations of thrombin (0.05 U/ml) or PAR1-activating peptide (PAR1-AP, 20 μM) were reduced or abolished as a result of the blockade of PHBs by anti-PHB antibodies or their Fab fragments; however, the same results were not observed when induced by high concentrations of thrombin (0.6 U/ml) or PAR4-AP (300 μM). The calcium mobilization in MEG-01 megakaryocytes stimulated by PAR1-AP was significantly suppressed by PHB depletion using RNA interference against PHB1 and PHB2. Conclusions: PHBs are localized on the human platelet membrane and are involved in PAR1-mediated platelet aggregation. Until recently, PHBs were unknown regulators of PAR1 signaling and may be effective targets for anti-platelet therapy.

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