Developmental expression of plasminogen activator inhibitor-1 associated with thrombopoietin-dependent megakaryocytic differentiation.
Plasminogen activator inhibitor-1 (PAI-1) is present in the platelet alpha-granule and is released on activation. However, there is some debate as to whether the megakaryocyte and platelet synthesize PAI-1, take it up from plasma, or both. We examined the expression of PAI-1 in differentiating megakaryocytic progenitor cells (UT-7) and in CD34(+)/CD41(-) cells from cord blood. UT-7 cells differentiated with thrombopoietin (TPO) resembled megakaryocytes (UT-7/TPO) with respect to morphology, ploidy, and the expression of glycoprotein IIb-IIIa. PAI-1 messenger RNA (mRNA) expression was upregulated and PAI-1 protein synthesized in the UT-7/TPO cells accumulated in the cytoplasm without being released spontaneously. In contrast, erythropoietin (EPO)-stimulated UT-7 cells (UT-7/EPO) did not express PAI-1 mRNA after stimulation with TPO because they do not have endogenous c-Mpl. After cotransfection with human wild-type c-mpl, the cells (UT-7/EPO-MPL) responded to phorbol 12-myristate 13-acetate (PMA), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) with enhanced PAI-1 mRNA expression within 24 to 48 hours. However, induction of PAI-1 mRNA in UT-7/EPO-MPL cells by TPO required at least 14-days stimulation. UT-7/EPO cells expressing c-Mpl changed their morphology and the other characteristics similar to the UT-7/TPO cells. TPO also differentiated human cord blood CD34(+)/CD41(-) cells to CD34(-)/CD41(+) cells, generated morphologically mature megakaryocytes, and induced the expression of PAI-1 mRNA. These results suggest that both PAI-1 mRNA and de novo PAI-1 protein synthesis is induced after differentiation of immature progenitor cells into megakaryocytes by TPO.
Division of Hemostasis and Thrombosis, Institute of Hematology, Division of Hematology, Department of Medicine, Jichi Medical School, Tochigi-ken, Japan.
S
S
Madoiwa
N
N
Komatsu
J
J
Mimuro
K
K
Kimura
M
M
Matsuda
Y
Y
Sakata
D015415:Biomarkers; D002454:Cell Differentiation / Q000187:drug effects; D003114:Colony-Forming Units Assay; D018076:DNA, Complementary / Q000235:genetics; D004921:Erythropoietin / Q000494:pharmacology; D005312:Fetal Blood / Q000166:cytology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D006801:Humans; D007947:Leukemia, Megakaryoblastic, Acute / Q000473:pathology; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013926:Thrombopoietin / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D015415:Biomarkers; D018076:DNA, Complementary; D009363:Neoplasm Proteins; D017395:Plasminogen Activator Inhibitor 1; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins; D004921:Erythropoietin; C082218:MPL protein, human; D013926:Thrombopoietin; D013755:Tetradecanoylphorbol Acetate