Demonstration of an activation regulated NF-κB/I-κBα complex in human platelets

In eukaryotic cells, the ubiquity of the signaling system of transcription factor nuclear factor-kappa B (NF-κB)/I-kappa B (I-κB) is undisputed. Numerous studies have reported that the NF-κB/I-κB complex plays a pivotal role in regulating gene expression controlling cell differentiation, cell proliferation, inflammation, oncogenesis, and apoptosis. Here we show that NF-κB/I-κB families exist in human platelets, natural anuclear corpuscles derived from megakaryocytes. Moreover, the I-κB kinase (IKK) is present and may phosphorylate I-κB during platelet activation. Coupled with intracellular calcium flux, this leads to I-κB dissociation from the NF-κB/I-κB complex and proteolysis. The NF-κB/I-κB proteins may have function independent of gene regulation in platelets.