title: IκB kinase phosphorylation of SNAP-23 controls platelet secretion.
abstract: Platelet secretion plays a key role in thrombosis, thus the platelet secretory machinery offers a unique target to modulate hemostasis. We report the regulation of platelet secretion via phosphorylation of SNAP-23 at Ser95. Phosphorylation of this t-soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) occurs upon activation of known elements of the platelet signaling cascades (ie, phospholipase C, [Ca(2+)]i, protein kinase C) and requires IκB kinase (IKK)-β. Other elements of the nuclear factor κB/IκB cascade (ie, IKK-α,-β,-γ/NEMO and CARMA/MALT1/Bcl10 complex) are present in anucleate platelets and IκB is phosphorylated upon activation, suggesting that this pathway is active in platelets and implying a nongenomic role for IKK. Inhibition of IKK-β, either pharmacologically (with BMS-345541, BAY11-7082, or TPCA-1) or by genetic manipulation (platelet factor 4 Cre:IKK-β(flox/flox)), blocked SNAP-23 phosphorylation, platelet secretion, and SNARE complex formation; but, had no effect on platelet morphology or other metrics of platelet activation. Consistently, SNAP-23 phosphorylation enhanced membrane fusion of SNARE-containing proteoliposomes. In vivo studies with IKK inhibitors or platelet-specific IKK-β knockout mice showed that blocking IKK-β activity significantly prolonged tail bleeding times, suggesting that currently available IKK inhibitors may affect hemostasis.
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Zubair A
authors.initials: ZA
authors.lastname: Karim
authors.forename: Jinchao
authors.initials: J
authors.lastname: Zhang
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Banerjee
authors.forename: Michael C
authors.initials: MC
authors.lastname: Chicka
authors.forename: Rania
authors.initials: R
authors.lastname: Al Hawas
authors.forename: Tara R
authors.initials: TR
authors.lastname: Hamilton
authors.forename: Paul A
authors.initials: PA
authors.lastname: Roche
authors.forename: Sidney W
authors.initials: SW
authors.lastname: Whiteheart
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D006487:Hemostasis / Q000502:physiology; D051550:I-kappa B Kinase / Q000235:genetics* / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation / Q000502:physiology; D015539:Platelet Activation / Q000502:physiology*; D050766:Qb-SNARE Proteins / Q000378:metabolism*; D050767:Qc-SNARE Proteins / Q000378:metabolism*; D050600:SNARE Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D050600:SNARE Proteins; C107017:Snap23 protein, mouse; D051550:I-kappa B Kinase