Send to

Choose Destination
See comment in PubMed Commons below
Proc Natl Acad Sci U S A. 1998 May 12;95(10):5556-61.

Signal-dependent translation of a regulatory protein, Bcl-3, in activated human platelets.

Author information

Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA.


Circulating human platelets lack nuclei, cannot synthesize mRNA, and are considered incapable of regulated protein synthesis. We found that thrombin-activated, but not resting, platelets synthesize Bcl-3, a member of the IkappaB-alpha family of regulatory proteins. The time- and concentration-dependent generation of Bcl-3 in platelets signaled by thrombin was blocked by translational inhibitors, by rapamycin, and by inhibitors of phosphatidylinositol-3-kinase, indicating that it occurs via a specialized translational control pathway that involves phosphorylation of the inhibitory protein 4E-BP1. After its synthesis in activated platelets Bcl-3 binds to the SH3 domain of Fyn (p59(fyn)), a Src-related tyrosine kinase. This, along with its expression in anucleate cells, suggests that Bcl-3 has previously unrecognized functions aside from modulation of transcription. We also demonstrate that platelets synthesize and secrete numerous proteins besides Bcl-3 after they adhere to fibrinogen, which mediates adhesion and outside-in signaling of these cells by engagement of alphaIIb/beta3 integrin. Taken together, these data demonstrate that regulated synthesis of proteins is a signal-dependent activation response of human platelets.

[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center