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Updated: Feb 25, 2026

Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
Published on: May 23, 2025
Platelet factor XI: intracellular localization and mRNA splicing following platelet activation
M Zucker1, H Hauschner1, U Seligsohn1
1The Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel Aviv University, Israel.
Background:
The structure and function of platelet factor XI (FXI) protein and the presence of F11 mRNA in platelets are controversial. Although platelets are anucleated cells they contain spliceosome components and pre-mRNAs. Three platelet proteins have been demonstrated to be spliced upon platelet activation.
Objective:
To determine whether FXI is also spliced upon activation and to discern the localization of FXI in platelets.
Methods:
Localization of FXI in platelets was assessed by confocal immunofluorescence staining. ELISA, chromogenic assay and western blot analyses were used to measure antigen levels, activity levels and size of FXI in platelets, respectively. Splicing patterns of F11 mRNA were assessed in three states of platelet activation: activated platelets, resting platelets and αIIbβ3-integrin activated platelets.
Results:
Platelet FXI was exhibited in platelet granules. Activated platelets exhibited higher levels of mature F11 mRNA and protein and lower levels of F11 pre-mRNA compared to resting or αIIbβ3-integrin activated platelets.
Conclusions:
We confirmed the presence of FXI in platelets and showed that it is localized in granules but is not restricted to the same α-granule subtype as von-Willebrand factor and p-selectin. Our study also shows that F11 is present in platelets as pre-mRNA and is spliced upon platelet activation.
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