Activation mechanism dependent surface exposure of cellular factor XIII on activated platelets and platelet microparticles

Laura Somodi, Ildikó Beke Debreceni, Gréta Kis, Marco Cozzolino, János Kappelmayer, Miklós Antal, György Panyi, Helga Bárdos, Nicola Mutch, László Muszbek* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Background: Platelets contain a high amount of potentially active A subunit dimer of coagulation factor XIII (cellular FXIII; cFXIII). It is of cytoplasmic localization, not secreted, but becomes translocated to the surface of platelets activated by convulxin and thrombin (CVX+Thr).
Objective: To explore the difference in cFXIII translocation between receptor mediated and non-receptor mediated platelet activation and if translocation can also be detected on platelet-derived microparticles. Our aim was also to shed some light on the mechanism of cFXIII translocation.
Methods: Gel-filtered platelets were activated by CVX+Thr or Ca2+-ionophore (calcimycin). The translocation of cFXIII and phosphatidylserine (PS) to the surface of activated platelets and platelet-derived microparticles was investigated by flow cytometry, immunofluorescence and immune electron microscopy. Fluo-4-AM fluorescence was used for the measurement of intracellular Ca2+ concentration.
Results: Receptor mediated activation by CVX+Thr exposed cFXIII to the surface of over 60% of platelets. Electron microscopy revealed microparticles with preserved membrane structure and microparticles devoid of labeling for membrane glycoprotein CD41a. cFXIII was observed on both types of microparticles but was more abundant in the absence of CD41a. Rhosin, a RhoA inhibitor significantly decreased cFXIII translocation. Non-receptor mediated activation of platelets by calcimycin elevated intracellular Ca2+ concentration, induced the translocation of PS to the surface of platelets and microparticles, but failed to expose cFXIII.
Conclusions: The elevation of intracellular Ca2+ concentration is sufficient for the translocation of PS from the internal layer of the membrane, while the translocation of cFXIII from the platelet cytoplasm requires additional receptor mediated mechanism(s).
Original languageEnglish
Pages (from-to)1223–1235
Number of pages13
JournalJournal of Thrombosis and Haemostasis
Issue number5
Early online date21 Feb 2022
Publication statusPublished - 20 Apr 2022


  • cell-derived microparticles
  • factor XIII
  • flow cytometry
  • immune electron microscopy
  • platelet activation


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