Integrin αIIbβ3-Dependent ERK Signaling Is Regulated by Src and Rho Kinases in Both Leu33 and Pro33 Polymorphic Isoforms

A Nano-Based P1Cminimum Probe to Monitor Thrombosis in Grafts and Improve Cardiac Function After Coronary Artery Bypass Grafting Surgery

Magnetic resonance imaging is widely used to identify and monitor thrombi in grafted vessels following coronary artery bypass grafting surgery (CABG). We produced a biosensor, P1Cm-SPIO-Cy5.5, composed of P1Cm peptide, superparamagnetic iron oxide nanoparticles (SPIO), and polyethylene glycol (PEG), for use in MRI thrombus imaging. Activated platelets induced by adenosine diphosphate were used for combination tests in vitro. A rat model of common carotid artery thrombosis was used for anti-thrombus experiments in vivo. P1Cm-SPIO-Cy5.5 remains stable in vitro and has good anticoagulation capacity. It can bind specifically to activated platelets and thrombi. In rats that underwent bypass surgery, P1Cm-SPIO-Cy5.5 could detect and label thrombi over a long period, and prevent thrombosis in grafted vessels. P1Cm-SPIO-Cy5.5 improved cardiac function in rats following CABG surgery. P1Cm-SPIO-Cy5.5 is a potential sensor for use in MRI for the early diagnosis and prevention of thrombosis after CABG surgery.

Leu33Pro (PlA) polymorphism of integrin beta3 modulates platelet Src pY418 and focal adhesion kinase pY397 phosphorylation in response to abnormally high shear stress

OBJECTIVES

Shear stress can activate platelet integrin-mediated signaling that leads to shear-induced platelet aggregation (SIPA) and eventually contribute to acute myocardial infarction. The major platelet integrin αIIbβ3 is polymorphic at residue 33 [Leu33Pro (PlA) polymorphism]. The Pro33 isoform has been shown to have a prothrombotic phenotype. In this work, we studied the impact of Leu33/Pro33 polymorphism on the shear-induced integrin-mediated Src and FAK activation in platelets.

METHODS

Platelets of both genotypes were placed on immobilized fibrinogen or heat activated BSA and were exposed to physiological (500/s) or abnormally high (5000/s) shear rates for 2-10 min. Platelets after exposure to shear were analysed for Src pY418 and FAK pY397 activities.

RESULTS

Whereas physiological shear stress does not affect platelet signaling, abnormally high-shear stress considerably elevates Src and FAK phosphorylation in both Pro33 and Leu33 platelets. Both under static and flow conditions, Pro33 platelets exhibited a significantly higher Src and FAK activities than Leu33 platelets. Interestingly, even in the absence of the αIIbβ3-fibrinogen interaction, we could detect a shear-induced integrin-mediated signaling of Src and FAK in platelets. In parallel experiments in which platelets were pretreated with abciximab, an integrin αIIbβ3 antagonist, activation of both kinases by shear was inhibited.

CONCLUSION

Taken together, our data indicates an important role of αIIbβ3 and shows that Leu33Pro polymorphism modulates the integrin-mediated Src and FAK signaling in platelets in response to shear stress.