Disease relevance of PF4

• GAGs which can neutralize PF4 and which can also have specific anti-factor Xa activity could represent a great advantage in thrombosis prophylaxis [1].

High impact information on PF4

• The effects of PF-4 were antagonized by heparin [2].
• PF-4 inhibited DNA synthesis, as well as proliferation of endothelial cells derived from large and small blood vessels [2].
• Inhibition of cell growth by PF-4 was reversible [2].
• In cells synchronized in S phase by hydroxyurea and then released, addition of PF-4 promptly blocked further progression of DNA synthesis [2].
• The addition of c7E3 Fab also significantly prolonged the ACTs of blood anticoagulated with the direct thrombin inhibitors hirudin and D-phenylalanyl-L-prolyl-L-arginyl chloromethyl ketone, indicating that the effect of c7E3 Fab was not exclusively related to decreased release of PF4, a heparin-neutralizing factor, from platelets [3].

Biological context of PF4

• RESULTS: The overall incidence of heparin-PF4 antibody formation was 42% [4].
• Platelet counts and heparin-PF4 antibody tests (enzyme-linked immunosorbent assays) were performed preoperatively and daily until postoperative day 7 or discharge if earlier [4].
• The heparin binding site of ovine PF4 localized in the C-terminal region of the molecule was identified as LYKKIIKRLL [5].

Anatomical context of PF4

• When PF4 was added to the medium of cells, attachment on either substratum was unaffected as was neurite outgrowth on pFN, revealing differences in PF4's inhibition as the substratum-bound or medium-borne component [6].
• We utilized platelet factor 4 (PF4) conjugated to fluorescein to stain the proteoglycans of permeabilized fixed bovine aorta endothelial cells in monolayer culture [7].
• CONCLUSIONS: This study confirms the high frequency of heparin-PF4 antibodies after coronary artery bypass grafting and demonstrates a significantly higher incidence after bovine heparin [4].
• From activated human leukocyte culture supernatants, we have isolated a form of PF-4 that acts as a potent inhibitor of endothelial cell proliferation [8].
• Involvement of hepatocyte nuclear factor-4 in the expression of the growth hormone receptor 1A messenger ribonucleic acid in bovine liver [9].

Associations of PF4 with chemical compounds

• These differences should significantly affect the secondary structure and heparin-binding properties of the protein based on considerations of the bovine PF4 crystal structure [10].
• Aggregation and release of 14C-serotonin and PF4 were inhibited by the metabolic inhibitors 2-deoxyglucose (16.7 mM) and antimycin-A (8.3 micrograms/ml), by the membrane-active drugs mepacrine (10 microM) and chlorpromazine (0.025 mM), by PGI2 (5.34 nM), which elevates intracellular c-AMP, by indomethacin (10 microM) or aspirin (100 microM) [11].
• In vitro, PF4 is comparable to protamine sulfate in the neutralization of heparin, but the complexes formed with heparin are different [12].
• The content of PF4 determined by radioimmunoassay was 22.6 (+/- 1.6 S.D.) micrograms per 10(9) platelets and 46.8 (+/- 19.6 S.D.) ng per ml platelet poor plasma collected in acid citrate dextrose in the presence of prostaglandin E1 [5].
• The relative degree of both kallikrein activation and PF4 release was greater in the non-fixed tissue but a greater number of fibrin(ogen) molecules per cm2 was found on GA-treated tissue [13].

Other interactions of PF4

• Immunohistochemically, staining for the octamer-binding transcription factor 4 (OCT4, also known as POU5F1), revealed a specific and exclusive staining of nuclei of the complete epiblast [14].

References