T A Sovershaev1, E M Egorina2, D Unruh3, V Y Bogdanov3, J B Hansen4, M A Sovershaev5. 1. K.G. Jebsen Thrombosis and Expertise Centre (TREC), Tromsø, Norway; Hematological Research Group, Department of Clinical Medicine, the Faculty of Health Sciences, University of Tromsø, N-9037, Tromsø, Norway; Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA. Electronic address: timofey.sovershaev@uit.no. 2. Section for Clinical Pharmacology, University Hospital of North Norway, N-9038, Tromsø, Norway. 3. Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, 45267, USA. 4. K.G. Jebsen Thrombosis and Expertise Centre (TREC), Tromsø, Norway; Hematological Research Group, Department of Clinical Medicine, the Faculty of Health Sciences, University of Tromsø, N-9037, Tromsø, Norway; Division of Internal Medicine, University Hospital of North Norway, N-9038, Tromsø, Norway. 5. Hematological Research Group, Department of Clinical Medicine, the Faculty of Health Sciences, University of Tromsø, N-9037, Tromsø, Norway; Section for Medical Biochemistry, Department of Laboratory Medicine, University Hospital of Northern Norway, N-9038, Tromsø, Norway.
Abstract
BACKGROUND: Bone morphogenetic protein (BMP)-7, a major regulator of bone metabolism, inhibits ectopic calcification in atherosclerotic plaques. We have recently reported that BMP-7 is also a potent inducer of tissue factor (TF) in human mononuclear cells (MNCs). While nuclear factor kappa beta (NF-kB) and activation protein-1 (AP-1) are the transcription factors essential for inducible expression of human TF gene (F3), the mechanisms responsible for TF induction by BMP-7 are not known. OBJECTIVE: To elucidate the molecular mechanisms governing BMP-7-triggered TF expression in human MNCs. METHODS: Human blood monocytes were stimulated with BMP-7 and western blotting, qRT-PCR, and flow cytometry studies were carried out to assess F3 expression; promoter studies were also performed using a panel of reporter constructs. Procoagulant TF activity was measured using a validated FXa generation assay. The significance of NF-kB transcriptional activity was verified via pharmacological inhibition. RESULTS: BMP-7 increased TF protein levels, procoagulant activity, surface presentation, and TF mRNA expression. This increase was accompanied by activation of NF-kB as evidenced by reduced IkB-α levels and elevated transcriptional activity of an NF-kB-sensitive reporter in transfected MNCs. Although treatment with BMP-7 also led to a strong phosphorylation of c-Jun, activation of AP-1 alone was not sufficient to induce TF expression: JSH-23, a potent and specific NF-kB inhibitor, completely blocked BMP-7-induced TF expression. CONCLUSIONS: We report that BMP-7-dependent activation of TF in human MNCs is mediated via increased activity of NF-kB, leading to enhanced F3 transcription in human MNCs.
BACKGROUND:Bone morphogenetic protein (BMP)-7, a major regulator of bone metabolism, inhibits ectopic calcification in atherosclerotic plaques. We have recently reported that BMP-7 is also a potent inducer of tissue factor (TF) in human mononuclear cells (MNCs). While nuclear factor kappa beta (NF-kB) and activation protein-1 (AP-1) are the transcription factors essential for inducible expression of humanTF gene (F3), the mechanisms responsible for TF induction by BMP-7 are not known. OBJECTIVE: To elucidate the molecular mechanisms governing BMP-7-triggered TF expression in human MNCs. METHODS:Human blood monocytes were stimulated with BMP-7 and western blotting, qRT-PCR, and flow cytometry studies were carried out to assess F3 expression; promoter studies were also performed using a panel of reporter constructs. Procoagulant TF activity was measured using a validated FXa generation assay. The significance of NF-kB transcriptional activity was verified via pharmacological inhibition. RESULTS:BMP-7 increased TF protein levels, procoagulant activity, surface presentation, and TF mRNA expression. This increase was accompanied by activation of NF-kB as evidenced by reduced IkB-α levels and elevated transcriptional activity of an NF-kB-sensitive reporter in transfected MNCs. Although treatment with BMP-7 also led to a strong phosphorylation of c-Jun, activation of AP-1 alone was not sufficient to induce TF expression: JSH-23, a potent and specific NF-kB inhibitor, completely blocked BMP-7-induced TF expression. CONCLUSIONS: We report that BMP-7-dependent activation of TF in human MNCs is mediated via increased activity of NF-kB, leading to enhanced F3 transcription in human MNCs.