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The GPIbα intracellular tail – role in transducing VWF- and collagen/GPVI-mediated signaling

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Title: The GPIbα intracellular tail – role in transducing VWF- and collagen/GPVI-mediated signaling
Authors: Constantinescu-Bercu, A
Wang, YA
Woollard, KJ
Mangin, P
Vanhoorelbeke, K
Crawley, JTB
Salles-Crawley, II
Item Type: Journal Article
Abstract: <jats:p>The GPIbT-VWF A1 domain interaction is essential for platelet tethering under high shear. Synergy between GPIbα and GPVI signaling machineries has been suggested previously, however its molecular mechanism remains unclear. We generated a novel GPIbα transgenic mouse (GpIbαΔsig/Δsig) by CRISPR-Cas9 technology to delete the last 24 residues of the GPIbα intracellular tail that harbors the 14-3-3 and phosphoinositide-3 kinase binding sites. GPIbαΔsig/Δsig platelets bound VWF normally under flow. However, they formed fewer filopodia on VWF/botrocetin in the presence of a oIIbI3 blocker, demonstrating that despite normal ligand binding, VWF-dependent signaling is diminished. Activation of GpIbαΔsig/Δsig platelets with ADP and thrombin was normal, but GpIbαΔsig/Δsig platelets stimulated with collagen-related-peptide (CRP) exhibited markedly decreased P-selectin exposure and eIIbI3 activation, suggesting a role for the GpIbaaintracellular tail in GPVI-mediated signaling. Consistent with this, while haemostasis was normal in GPIbαΔsig/Δsig mice, diminished tyrosine-phosphorylation, (particularly pSYK) was detected in CRP-stimulated GpIbαΔsig/Δsig platelets as well as reduced platelet spreading on CRP. Platelet responses to rhodocytin were also affected in GpIbαΔsig/Δsig platelets but to a lesser extent than those with CRP. GpIbαΔsig/Δsig platelets formed smaller aggregates than wild-type platelets on collagen-coated microchannels at low, medium and high shear. In response to both VWF and collagen binding, flow assays performed with plasma-free blood or in the presence of bIIbI3- or GPVI-blockers suggested reduced bIIbI3 activation contributes to the phenotype of the GpIbαΔsig/Δsig platelets. Together, these results reveal a new role for the intracellular tail of GPIbiiin transducing both VWF-GPIbGGand collagen-GPVI signaling events in platelets.</jats:p>
Issue Date: 1-Apr-2022
Date of Acceptance: 10-Jun-2021
URI: http://hdl.handle.net/10044/1/90389
DOI: 10.3324/haematol.2020.278242
ISSN: 0390-6078
Publisher: Ferrata Storti Foundation (Haematologica)
Start Page: 933
End Page: 946
Journal / Book Title: Haematologica
Volume: 107
Issue: 4
Copyright Statement: © 2021 Ferrata Storti Foundation. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/)
Sponsor/Funder: British Heart Foundation
Funder's Grant Number: PG/17/22/32868
Keywords: Animals
Blood Platelets
Signal Transduction
von Willebrand Factor
1102 Cardiorespiratory Medicine and Haematology
Publication Status: Published
Online Publication Date: 2021-06-17
Appears in Collections:Department of Immunology and Inflammation
Faculty of Medicine

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