title: Cardiac glycosides regulate endothelial tissue factor expression in culture.
abstract: 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.
authors.affiliation: Cardiovascular Research, Physiology Institute, University of Zürich and Cardiology, University Hospital Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland. felix.tanner@access.unizh.ch.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Stähli
authors.forename: Alexander
authors.initials: A
authors.lastname: Breitenstein
authors.forename: Alexander
authors.initials: A
authors.lastname: Akhmedov
authors.forename: Giovanni G
authors.initials: GG
authors.lastname: Camici
authors.forename: Kushiar
authors.initials: K
authors.lastname: Shojaati
authors.forename: Nikolay
authors.initials: N
authors.lastname: Bogdanov
authors.forename: Jan
authors.initials: J
authors.lastname: Steffel
authors.forename: Daniel
authors.initials: D
authors.lastname: Ringli
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Lüscher
authors.forename: Felix C
authors.initials: FC
authors.lastname: Tanner
mesh_terms: 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
chemical_list: 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