Abstract Number: PB1753
Meeting: ISTH 2020 Congress
Background: Platelet activation is essential for hemostasis. Central to platelet activation are the signals transmitted through surface receptors such as GPVI and C-type lectin-like receptor 2 (CLEC-2). Both GPVI and CLEC-2 signal through spleen tyrosine kinase (Syk). Syk activity is dependent on phosphorylation of several residues including Y342, Y346, and Y519/520 (Y348, Y352, and Y525/526 in human). However, the importance of each residue on either phosphorylation of other residues or activation of Syk is unknown.
Aims: To determine the relative contribution of Syk Y342 on ITAM and hemITAM signaling, and platelet functional response.
Methods: We produced a Syk Y342F knock-in mouse line to investigate the importance of Y342 on Syk-mediated signaling using a platelet system.
Results: We were unable to detect any Syk Y342 phosphorylation following stimulation of Y342F platelets with the GPVI agonist collagen-related peptide (CRP). Platelet reactivity was reduced in response to the GPVI agonists CRP and collagen (Figure 1 A-B). When using CLEC-2 antibody as an agonist, no response was observed in Syk Y342F mouse platelets though control mouse platelets responded well (Figure 1C). Signaling initiated by either GPVI or CLEC-2 was also inhibited, as Syk Y519/520 phosphorylation is undetectable. Furthermore, SLP-76 phosphorylation was reduced in Syk Y342F platelets compared to platelets from littermate control mice following stimulation of GPVI. Hemostasis, as measured by tail bleeding time, was not altered in Syk Y342F mice, but thrombus formation in response to FeCl3 injury was prolonged in Syk Y342F mice (Figure 2 A-B).
Conclusions: These data demonstrate that phosphorylation of Y342 on Syk following stimulation of either ITAM or hemITAM-bearing receptors is important for the ability of Syk to transduce a signal.
To cite this abstract in AMA style:Kostyak J, Mauri B, Dangelmaier C, Patel A, Reddy H, Kunapuli S. Dysfunctional CLEC-2- and GPVI-mediated Signaling in Syk Y342F Knock-in Mouse Platelets [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/dysfunctional-clec-2-and-gpvi-mediated-signaling-in-syk-y342f-knock-in-mouse-platelets/. Accessed March 4, 2024.
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