Protein Tyrosine Kinase Activation Is Required for LPS and PMA Induction of Tissue Factor mRNA in Human Blood Monocytes

Abstract

SummaryTissue factor (TF) is a transmembrane glycoprotein which assembles with factor VIIa on cell surfaces to form a proteolytically active cofactor-enzyme complex; the TF/VIIa complex initiates the coagulation protease cascade. In response to bacterial lipopolysaccharide (LPS) and phorbol-12 myristate 13-acetate (PMA), monocytes synthesize and express TF on their surface. However, the mechanisms by which LPS and PMA activate TF synthesis by human blood monocytes are not fully understood. As it has been established that LPS and PMA activate protein tyrosine kinase (PTK) in monocytes, we studied the role of PTK in LPS and PMA induction of TF by human blood monocytes. Both LPS-and PMA-induced TF activity was inhibited in a concentration-dependent manner by the protein tyrosine kinase-specific inhibitors herbimycin A and genistein. TF antigen determination confirmed that LPS- and PMA-induced cell surface TF protein levels decreased in parallel to TF functional activity under herbimycin A and genistein treatment. Northern blot analysis of total RNA from LPS- and PMA-stimulated monocytes showed a concentration-dependent decrease in TF mRNA levels in response to herbimycin A and genistein. The rate of decay of LPS-induced TF mRNA, evaluated after the arrest of transcription by actinomycin D was not affected by genistein and herbimycin A, suggesting that the inhibitory effects occur at least partly at the transcriptional level. We conclude that LPS- and PMA-induced TF production by human monocytes is dependent on tyrosine kinase activation.

Role of Oxygen Radicals in Tissue Factor Induction by Endotoxin in Blood Monocytes

“…The last one is activated only by LPS and is independent of free radicals since DDD, SNP, or H2O2, in the absence of LPS, is unable to induce significant amounts of TF on monocytes. This third factor could be the acti vation of a phosphorylation cascade [17] eith er directly triggered by LPS or by platelet-acti vating factor [18], In addition, the synergistic effect of 07 and NO observed in the presence of DPI ( fig. 3B) suggests that these two reac tive oxygen species act on two distinct targets.…”

Tissue factor upregulation drives a thrombosis–inflammation circuit in relation to cardiovascular complications

“…TF expression is generally mediated by the activation of intracellular signalling (Table 1) involving protein tyrosine kinase (PTK), mitogen-activating protein kinases (MAPK) (Erk1/2 and p38 MAPK), 16,24,25,28,32,[48][49][50] protein kinase C (PKC), [51][52][53][54] or transcription factors (activator protein-1 (AP-1), nuclear factor-kappa B (NF-B) or early growth response-1 (Egr-1)). 16,23,24,28,36,49,55 The negative correlation of TF expression with intracellular cAMP level has been reported in many cells [56][57][58][59][60][61] (Table 1) 65 Angiopoietin downregulates TF expression.…”

Antagonism by IL-4 and IL-10 of Endotoxin-Induced Tissue Factor Activation in Monocytic THP-1 Cells: Activating Role of CD14 Ligation

“…21]. Thus far, LPS is known to stimulate TF synthesis as evidenced by the increased level of TF mRNA in different types of cells [22][23][24]; this stimulation has recently been reported to require the activation of protein tyrosine kinase (TK) [23].…”