Cardiac glycosides regulate endothelial tissue factor expression in culture.
BACKGROUND
Tissue factor (TF) plays an important role in acute coronary syndromes and stent thrombosis. This study investigates whether Na(+)/K(+)-ATPase regulates TF expression in human endothelial cells.


RESULTS
Ouabain inhibited tumor necrosis factor (TNF)-alpha-induced endothelial TF protein expression; maximal inhibition occurred at 10(-5) mol/L, reached more than 70%, and was observed throughout the 5 hours stimulation period. The decrease in protein expression was paralleled by a reduced TF surface activity. Similarly, lowering of extracellular potassium concentration inhibited TNF-alpha-induced TF protein expression. In contrast, ouabain did not affect TNF-alpha-induced expression of full-length TF mRNA for up to 5 hours of stimulation; instead, expression of alternatively-spliced TF mRNA was upregulated after 3 and 5 hours of stimulation. Ouabain did not affect TNF-alpha-induced activation of the MAP kinases p38, extracellular signal-regulated kinase (ERK), and c-Jun terminal NH(2) kinase; activation of Akt and p70S6 kinase remained unaltered as well. Similar to the MAP kinases, ouabain did not affect TNF-alpha-induced degradation of IkappaB-alpha. Ouabain had no effect on TF protein degradation.


CONCLUSIONS
Na(+)/K(+)-ATPase is required for protein translation of endothelial TF in culture. This observation provides novel insights into posttranscriptional regulation of TF expression.
Stähli
Barbara E
BE
Cardiovascular Research, Physiology Institute, University of Zürich and Cardiology, University Hospital Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland. felix.tanner@access.unizh.ch.
Breitenstein
Alexander
A
Akhmedov
Alexander
A
Camici
Giovanni G
GG
Shojaati
Kushiar
K
Bogdanov
Nikolay
N
Steffel
Jan
J
Ringli
Daniel
D
Lüscher
Thomas F
TF
Tanner
Felix C
FC
D017398:Alternative Splicing / Q000187:drug effects; D002301:Cardiac Glycosides / Q000494:pharmacology*; D002478:Cells, Cultured; D004077:Digoxin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013925:Thromboplastin / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
D002301:Cardiac Glycosides; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D010042:Ouabain; D004077:Digoxin; D013925:Thromboplastin; D020928:Mitogen-Activated Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium