Format

Send to

Choose Destination
See comment in PubMed Commons below
Biochem Biophys Res Commun. 2014 Jul 4;449(3):357-63. doi: 10.1016/j.bbrc.2014.05.032. Epub 2014 May 17.

Time-dependent inhibitory effects of cGMP-analogues on thrombin-induced platelet-derived microparticles formation, platelet aggregation, and P-selectin expression.

Author information

1
Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway.
2
Department of Biomedicine, University of Bergen, Bergen, Norway.
3
Department of Biomedicine, University of Bergen, Bergen, Norway; Molecular Biology Institute of Barcelona (IBMB, CSIC), Barcelona, Spain.
4
Proteomic Unit at University of Bergen (PROBE), University of Bergen, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway. Electronic address: Frode.Selheim@biomed.uib.no.

Abstract

In platelets, nitric oxide (NO) activates cGMP/PKG signalling, whereas prostaglandins and adenosine signal through cAMP/PKA. Cyclic nucleotide signalling has been considered to play an inhibitory role in platelets. However, an early stimulatory effect of NO and cGMP-PKG signalling in low dose agonist-induced platelet activation have recently been suggested. Here, we investigated whether different experimental conditions could explain some of the discrepancy reported for platelet cGMP-PKG-signalling. We treated gel-filtered human platelets with cGMP and cAMP analogues, and used flow cytometric assays to detect low dose thrombin-induced formation of small platelet aggregates, single platelet disappearance (SPD), platelet-derived microparticles (PMP) and thrombin receptor agonist peptide (TRAP)-induced P-selectin expression. All four agonist-induced platelet activation phases were blocked when platelets were costimulated with the PKG activators 8-Br-PET-cGMP or 8-pCPT-cGMP and low-doses of thrombin or TRAP. However, extended incubation with 8-Br-PET-cGMP decreased its inhibition of TRAP-induced P-selectin expression in a time-dependent manner. This effect did not involve desensitisation of PKG or PKA activity, measured as site-specific VASP phosphorylation. Moreover, PKG activators in combination with the PKA activator Sp-5,6-DCL-cBIMPS revealed additive inhibitory effect on TRAP-induced P-selectin expression. Taken together, we found no evidence for a stimulatory role of cGMP/PKG in platelets activation and conclude rather that cGMP/PKG signalling has an important inhibitory function in human platelet activation.

KEYWORDS:

PKG; Platelets; VASP; cAMP; cGMP; cGMP-analogues

PMID:
24845383
DOI:
10.1016/j.bbrc.2014.05.032
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center