Quercitrin regulates GPVI-mediated platelet activation via PTPs
activation
Previous research demonstrated that intracellular ROS participate in the
regulation of protein tyrosine phosphorylation by oxidizing the
catalytic cysteine residues of PTPs (SHP1, SHP2, and PTEN), which play a
negative regulatory role in GPVI-mediated platelet activation.(Jang et
al., 2014; Senis, 2013) Since quercitrin serves as an antioxidant, we
next examined whether quercitrin affects the activation of PTPs during
platelet activation. We found that the phosphorylation levels of SHP1,
SHP2, and PTEN were increased in CRP-activated vehicle–pretreated
platelets, whereas their phosphorylation was abrogated by quercitrin
treatment in a concentration-dependent manner (Figure 6E and 6F). These
results suggest that ROS generation upon GPVI stimulation leads to PTP
inactivation and promotes tyrosine phosphorylation-based signal
transduction, whereas quercitrin, as an anti-oxidant, scavenges ROS and
promotes PTP dephosphorylation, thereby reducing GPVI-mediated platelet
activation.