Expression of prostacyclin receptor in human megakaryocytes.
Prostacyclin (prostaglandin I2, PGI2) is a potent vasodilator and inhibitor of platelet aggregation. Although it is well known that the specific receptor for prostacyclin (PGI2-R) is abundantly expressed on platelets, PGI2-R expression in megakaryocytes is poorly understood. In this study, we examined its expression in leukemic or normal megakaryocytes. PGI2-R mRNA was expressed in human leukemic cell lines of megakaryocytic nature as evaluated by Northern blot analysis. Phorbol 12-myristate 13-acetate (PMA), interleukin-1 (IL-1), IL-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), thrombopoietin (TPO), and tumor necrosis factor-alpha (TNF-alpha) enhanced PGI2-R mRNA expression. The enhancement of PGI2-R expression by PMA and TPO was associated with the upregulation of platelet factor 4 or glycoprotein IIb mRNA expression. Iloprost, an agonist of prostacyclin, induced significant cyclic (c)AMP synthesis in these leukemic cells indicating that interaction of PGI2-R and its ligand can induce postreceptor signal transduction. Furthermore, iloprost-induced cAMP synthesis was enhanced by the pretreatment with PMA or the cytokines that promoted PGI2-R expression. PMA and TPO also increased the specific binding of [3H]iloprost to these cells. Pooled normal megakaryocytic colonies from TPO-containing semisolid culture of purified human CD34+ cells expressed PGI2-R, which were increased as the megakaryocytes matured with the peak expression before proplatelet formation, as evaluated by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). These results indicate that PGI2-R is expressed in human megakaryocytes and is upregulated by cytokines involved in thrombopoiesis or inflammation. Also, it was indicated that megakaryocytic maturation accompanies enhancement of PGI2-R expression.
Sasaki
Y
Y
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, College of Medical Technology, Kyoto University, Japan.
Takahashi
T
T
Tanaka
I
I
Nakamura
K
K
Okuno
Y
Y
Nakagawa
O
O
Narumiya
S
S
Nakao
K
K
D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D018922:HL-60 Cells / Q000187:drug effects / Q000378:metabolism; D019337:Hematologic Neoplasms / Q000473:pathology; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D007378:Interleukins / Q000494:pharmacology; D007947:Leukemia, Megakaryoblastic, Acute / Q000473:pathology; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D010978:Platelet Factor 4 / Q000096:biosynthesis / Q000235:genetics; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000096:biosynthesis* / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007378:Interleukins; D009363:Neoplasm Proteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D005576:Colforsin; D010978:Platelet Factor 4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013926:Thrombopoietin; D000242:Cyclic AMP; D016285:Iloprost; D013755:Tetradecanoylphorbol Acetate