Summary
We have previously shown that the serine protease thrombin and other G protein-coupled
agonists acutely enhance synthesis and release of prostacyclin from human umbilical
vein endothelial cells (HUVEC) through activation of cPLA2α. Here, we show that thrombin and other physiological endothelial cell agonists upregulate
COX-2 induction in HUVEC. Thrombin treatment caused a rapid and sustained increase
in prostacyclin (PGI2) synthesis from HUVEC. Thrombin and a selective protease-activated receptor-1 (PAR-1)
peptide (TRAP) evoked doseand time-dependent increases in COX-2 protein expression
which were equivalent to that induced by the proinflammatory cytokine IL-1α. Quantitative
and real-time PCR analysis showed enhanced COX-2 mRNA expression in thrombinor TRAP-stimulated
HUVEC whereas COX-1 expression was unaffected. A PAR-2 agonist peptide also induced
COX-2 protein and mRNA expression with kinetics distinct from those of thrombin, and
promoted PGI2 release. These results demonstrate that regulation of COX-2 induction is an important
functional response of HUVEC to PAR activation and suggest that PARs promote sustained
upregulation of prostanoid production in human endothelium.
Keywords
Human endothelium - thrombin - cyclooxygenase - prostacyclin - protease-activated
receptors