BACKGROUND: Binding of von Willebrand factor to the platelet glycoprotein (GP)Ib-IX complex initiates a signaling cascade leading to integrin alpha(IIb)beta(3) activation, a key process in hemostasis and thrombosis. Interaction of 14-3-3zeta with the intracytoplasmic domain of GPIb appears to be a major effector of this activation pathway. OBJECTIVE: The aim of our study was to determine whether other members of the 14-3-3 family bind to GPIb-IX. RESULTS: In this study, western blot analyses showed that platelets also contain the 14-3-3beta, 14-3-3gamma, 14-3-3epsilon, 14-3-3eta and 14-3-3theta isoforms, but lack 14-3-3sigma. Coimmunoprecipitation studies in platelets and CHO transfectants demonstrated that all six 14-3-3 isoforms expressed in platelets, including, as previously reported, 14-3-3zeta, bind to GPIb-IX. In addition, their interaction was found to critically require the same GPIbalpha domains (580-590 and 605-610) already identified as essential for 14-3-3zeta binding, in agreement with the conservation of the sequence of the I-helix among these different isoforms. Pull-down experiments indicated that all six 14-3-3 isoforms present in platelets bind to GPIbbeta. In contrast, deletion or mutation of the GPIbbeta intracytoplasmic tail did not affect the interaction of GPIb-IX with the 14-3-3 isoforms, questioning the importance of this domain. CONCLUSIONS: Our study suggests that, to inhibit GPIb-induced integrin alpha(IIb)beta(3) activation, a more appropriate strategy than inhibiting individual 14-3-3 isoforms would be to target the 14-3-3-binding motif on GPIb or, alternatively, the conserved 14-3-3 I-helix.
BACKGROUND: Binding of von Willebrand factor to the platelet glycoprotein (GP)Ib-IX complex initiates a signaling cascade leading to integrin alpha(IIb)beta(3) activation, a key process in hemostasis and thrombosis. Interaction of 14-3-3zeta with the intracytoplasmic domain of GPIb appears to be a major effector of this activation pathway. OBJECTIVE: The aim of our study was to determine whether other members of the 14-3-3 family bind to GPIb-IX. RESULTS: In this study, western blot analyses showed that platelets also contain the 14-3-3beta, 14-3-3gamma, 14-3-3epsilon, 14-3-3eta and 14-3-3theta isoforms, but lack 14-3-3sigma. Coimmunoprecipitation studies in platelets and CHO transfectants demonstrated that all six 14-3-3 isoforms expressed in platelets, including, as previously reported, 14-3-3zeta, bind to GPIb-IX. In addition, their interaction was found to critically require the same GPIbalpha domains (580-590 and 605-610) already identified as essential for 14-3-3zeta binding, in agreement with the conservation of the sequence of the I-helix among these different isoforms. Pull-down experiments indicated that all six 14-3-3 isoforms present in platelets bind to GPIbbeta. In contrast, deletion or mutation of the GPIbbeta intracytoplasmic tail did not affect the interaction of GPIb-IX with the 14-3-3 isoforms, questioning the importance of this domain. CONCLUSIONS: Our study suggests that, to inhibit GPIb-induced integrin alpha(IIb)beta(3) activation, a more appropriate strategy than inhibiting individual 14-3-3 isoforms would be to target the 14-3-3-binding motif on GPIb or, alternatively, the conserved 14-3-3 I-helix.
Authors: Dianne E van der Wal; Eelo Gitz; Vivian X Du; Kimberly S L Lo; Cornelis A Koekman; Sabine Versteeg; Jan Willem N Akkerman Journal: Haematologica Date: 2012-02-27 Impact factor: 9.941
Authors: M Edward Quach; Wenchun Chen; Yingchun Wang; Hans Deckmyn; François Lanza; Bernhard Nieswandt; Renhao Li Journal: J Thromb Haemost Date: 2021-05-20 Impact factor: 16.036
Authors: Simone M Schoenwaelder; Roxane Darbousset; Susan L Cranmer; Hayley S Ramshaw; Stephanie L Orive; Sharelle Sturgeon; Yuping Yuan; Yu Yao; James R Krycer; Joanna Woodcock; Jessica Maclean; Stuart Pitson; Zhaohua Zheng; Darren C Henstridge; Dianne van der Wal; Elizabeth E Gardiner; Michael C Berndt; Robert K Andrews; David E James; Angel F Lopez; Shaun P Jackson Journal: Nat Commun Date: 2016-09-27 Impact factor: 14.919
Authors: Adela Constantinescu-Bercu; Yuxiao A Wang; Kevin J Woollard; Pierre Mangin; Karen Vanhoorelbeke; James T B Crawley; Isabelle I Salles-Crawley Journal: Haematologica Date: 2022-04-01 Impact factor: 11.047