Nuclear emancipation: a platelet tour de force.

Mammalian platelets are anucleate cells produced by the polyploid megakaryocyte. Platelets are more than just key players in hemostasis (blood clotting in response to injury); they also have important roles in inflammation, immunity, tumor progression, and thrombosis. Complex systems of homeostasis have been described for platelets, including posttranscriptional and translational mechanisms to regulate platelet function. Platelets contain transcription factors, and these proteins have essential roles in regulating nongenomic processes. A study provides evidence for a previously unknown negative feedback pathway for limiting platelet activation that occurs through the nuclear factor κB transcription factor family. This pathway is mediated by an adenosine 3',5'-monophosphate-independent protein kinase A activity in response to platelet stimulation. Our appreciation of the role of transcription factors in mammalian platelet biology is nascent but holds great promise for both understanding platelet function and translation into clinical uses.