title: Decreasing phosphodiesterase 5A activity contributes to platelet cGMP accumulation during storage of apheresis-derived platelet concentrates.
abstract: BACKGROUND
  Platelet storage lesion (PSL) considerably decreases the quality of platelets (PLTs) in concentrates characterized by a loss of signaling responses to agonists and impaired PLT activation, secretion, and aggregation. To understand the role of inhibitory signaling pathways in the mechanism of PSL, the basal state of the cyclic nucleotide (CN)-dependent signaling systems in stored PLTs was investigated.
  
  
  METHODS
  Whole blood samples (WB) and apheresis-derived PLT concentrates (APCs) were obtained from healthy volunteers. Washed PLTs were prepared from WB on Day 0 and from APCs on Days 0, 2, and 5. The basal phosphorylation of the vasodilator-stimulated phosphoprotein (VASP) and phosphodiesterase 5A (PDE5A) levels were quantified by Western blot. CN and PDE5A activity were measured by enzyme-linked immunoassay kits. Fibrinogen binding and aggregation were measured in PLT-rich plasma of WB or APC samples. Unpaired t test was used for statistical analysis.
  
  
  RESULTS
  Basal VASP phosphorylation levels were comparable in WB and APCs on Day 0. VASP phosphorylation increased significantly during storage of APCs, more pronounced at Ser(239) than at Ser(157) . Similarly, intracellular cGMP, but not cAMP, concentration continuously increased in stored PLTs, whereas PDE5A levels and activity significantly decreased accompanied by diminished thrombin receptor activator peptide 6-induced fibrinogen binding and aggregation.
  
  
  CONCLUSIONS
  Storage of APCs leads to intracellular cGMP accumulation that could be caused by degradation of PDE5A. Enhanced cGMP level supports subsequent cGMP-dependent protein kinase-mediated increase of VASP phosphorylation resulting in reduced fibrinogen binding and aggregation.
authors.affiliation: Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Kobsar
authors.forename: Evelyn
authors.initials: E
authors.lastname: Putz
authors.forename: Pinar
authors.initials: P
authors.lastname: Yilmaz
authors.forename: Elke
authors.initials: E
authors.lastname: Weinig
authors.forename: Markus
authors.initials: M
authors.lastname: Boeck
authors.forename: Juergen
authors.initials: J
authors.lastname: Koessler
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000201:enzymology*; D001793:Blood Preservation / Q000009:adverse effects*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D010446:Peptide Fragments / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects; D010983:Plateletpheresis / Q000009:adverse effects; D011485:Protein Binding / Q000187:drug effects; D055815:Young Adult; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; C082835:thrombin receptor peptide (42-47); D000098662:Vasodilator-Stimulated Phosphoprotein; D005340:Fibrinogen; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human; D006152:Cyclic GMP