Plasminogen activator inhibitor-1 mRNA is expressed in platelets and megakaryocytes and the megakaryoblastic cell line CHRF-288.
Plasminogen activator inhibitor-1 (PAI-1) is present in the platelet alpha-granule and is released on platelet activation. Platelet PAI-1 could either be synthesized by the megakaryocyte or taken up from the plasma. In this report we confirm the presence of PAI-1 protein in human megakaryocytes by Western blot analysis and show its synthesis in guinea pig megakaryocytes by metabolic labeling. We document the presence of PAI-1 mRNA in human platelets and show a 3-kb mRNA species on Northern blot analysis of guinea pig megakaryocytes. Neither untreated CHRF-288 cells, a megakaryoblastic cell line, nor human erythroleukemia (HEL) cells expressed PAI-1 mRNA. Phorbol ester (phorbol 12-myristate 13-acetate, 160 nM) treatment of CHRF-288 and HEL cells for 4 days induced PAI-1 mRNA expression in CHRF-288 cells but not in HEL cells. These studies show that PAI-1 is synthesized by megakaryocytes. Megakaryocytes most likely determine the PAI-1 content of platelets and thereby establish the antifibrinolytic potential of the platelet.
Konkle
B A
BA
Cardeza Foundation for Hematologic Research, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107.
Schick
P K
PK
He
X
X
Liu
R J
RJ
Mazur
E M
EM
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D015152:Blotting, Northern; D015153:Blotting, Western; D006168:Guinea Pigs; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D008533:Megakaryocytes / Q000378:metabolism*; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D013755:Tetradecanoylphorbol Acetate