| First Author | Constantinescu-Bercu A | Year | 2022 |
| Journal | Haematologica | Volume | 107 |
| Issue | 4 | Pages | 933-946 |
| PubMed ID | 34134470 | Mgi Jnum | J:357553 |
| Mgi Id | MGI:7524466 | Doi | 10.3324/haematol.2020.278242 |
| Citation | Constantinescu-Bercu A, et al. (2022) The GPIbalpha intracellular tail - role in transducing VWF- and collagen/GPVI-mediated signaling. Haematologica 107(4):933-946 |
| abstractText | The GPIbT-VWF A1 domain interaction is essential for platelet tethering under high shear. Synergy between GPIbalpha and GPVI signaling machineries has been suggested previously, however its molecular mechanism remains unclear. We generated a novel GPIbalpha transgenic mouse (GpIbalphaDeltasig/Deltasig) by CRISPR-Cas9 technology to delete the last 24 residues of the GPIbalpha intracellular tail that harbors the 14-3-3 and phosphoinositide-3 kinase binding sites. GPIbalphaDeltasig/Deltasig 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 GpIbalphaDeltasig/Deltasig platelets with ADP and thrombin was normal, but GpIbalphaDeltasig/Deltasig 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 GPIbalphaDeltasig/Deltasig mice, diminished tyrosine-phosphorylation, (particularly pSYK) was detected in CRP-stimulated GpIbalphaDeltasig/Deltasig platelets as well as reduced platelet spreading on CRP. Platelet responses to rhodocytin were also affected in GpIbalphaDeltasig/Deltasig platelets but to a lesser extent than those with CRP. GpIbalphaDeltasig/Deltasig 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 GpIbalphaDeltasig/Deltasig platelets. Together, these results reveal a new role for the intracellular tail of GPIbiiin transducing both VWF-GPIbGGand collagen-GPVI signaling events in platelets. |
