Regulation of endothelial cell tissue factor expression by minimally oxidized LDL and lipopolysaccharide.
Tissue factor (TF) is the predominant physiological initiator of coagulation, and its regulation is a critical aspect of endothelial cell hemostatic function. This report describes the regulation of TF mRNA expression by two physiological agonists: minimally oxidized low-density lipoprotein (MM-LDL), which may modulate endothelial hemostatic function in atherosclerosis, and lipopolysaccharide (LPS), which is a mediator of septic shock. Northern blot analysis of total RNA from human endothelial cells exposed to either MM-LDL or LPS for varying times showed that TF mRNA increased sharply at 1 hour, peaked at 2 to 3 hours, and declined to basal levels by 6 to 8 hours after treatment. The half-life of TF mRNA in MM-LDL- and LPS-exposed endothelial cells was approximately 45 minutes and 40 minutes, respectively. The rate of TF mRNA degradation was similar at 1 and 4 hours after exposure in either MM-LDL- or LPS-stimulated endothelial cells. Nuclear runoff transcription assays showed a significantly increased rate of TF gene transcription in both MM-LDL- and LPS-exposed endothelial cells. Cycloheximide inhibited the induction of TF protein activity, but it enhanced the accumulation of TF mRNA in MM-LDL- and LPS-induced endothelial cells. These results indicated that regulation of TF expression by MM-LDL and LPS in human endothelial cells occurs principally at the level of gene transcription.
Fei
H
H
Department of Pathology and Laboratory Medicine, UCLA School of Medicine 90024-1732.
Berliner
J A
JA
Parhami
F
F
Drake
T A
TA
D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004355:Drug Stability; D004730:Endothelium, Vascular / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006207:Half-Life; D006351:Heart Valves; D006801:Humans; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000378:metabolism; D013925:Thromboplastin / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D008070:Lipopolysaccharides; D008077:Lipoproteins, LDL; D012333:RNA, Messenger; D013925:Thromboplastin; D003513:Cycloheximide