The role of thrombin receptors PAR1 and PAR4 for PAI-1 storage, synthesis and secretion by human platelets
2012 (English)In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 129, no 4, E51-E58 p.Article in journal (Refereed) Published
Arterial thrombi contain more platelets than venous thrombi and are more resistant to fibrinolysis. This resistance could partly be due to plasminogen activator inhibitor 1 (PAI-1) secreted by platelets. The aim of this study was to elucidate differences between thrombin receptors protease-activated receptor (PAR) 1 and 4 and platelet storage, secretion and synthesis of platelet PAI-1, as compared to other platelet α-granule proteins such as VEGF and endostatin.
MATERIALS AND METHODS:
Human isolated platelets were incubated with thrombin (0.5U/ml), PAR1-activating peptide (AP) (0.4-30μM) or PAR4-AP (1.5-300μM) for up to 24hours. ELISA, western blot and fluorescence microscopy were used to measure secretion, contents and localization of PAI-1, VEGF and endostatin.
Our results show that PAI-1 and VEGF might be co-localized and that endostatin does not co-localize with either PAI-1 or VEGF. PAI-1 and VEGF show a similar secretion pattern, being more sensitive to low grade PAR1 activation, but secretion was also observed with higher concentrations of PAR4-APs. PAI-1 is secreted in an active form. PAI-1 mRNA was found in platelets, and elevated levels of PAI-1 were detected after 24hours incubation of platelets.
PAI-1 and VEGF, but not endostatin, might be stored in the same α-granule in human platelets. PAI-1 and VEGF also show a similar secretion pattern, being more sensitive to PAR1 than to PAR4 activation, but the secretion is not exclusively selective. Our results also show that platelet PAI-1 is increased if incubated for 24hours, both with addition of PAR1-activating peptide and without activation, which could indicate de novo synthesis.
Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 129, no 4, E51-E58 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-71393DOI: 10.1016/j.thromres.2011.12.021ISI: 000301587400010OAI: oai:DiVA.org:liu-71393DiVA: diva2:448087
funding agencies|Swedish Research Council| K2010-65X-15060-07-3 |strategic research area Cardiovascular Inflammation Research Center (CIRC)||County Council of Ostergotland||University of Linkoping||2011-10-142011-10-142015-03-13Bibliographically approved