Antithrombotic effects of targeting alphaIIbbeta3 signaling in platelets.

Abstract

alphaIIbbeta3 interaction with fibrinogen promotes Src-dependent platelet spreading in vitro. To determine the consequences of this outside-in signaling pathway in vivo, a "beta3(Delta760-762)" knockin mouse was generated that lacked the 3 C-terminal beta3 residues (arginine-glycine-threonine [RGT]) necessary for alphaIIbbeta3 interaction with c-Src, but retained beta3 residues necessary for talin-dependent fibrinogen binding. beta3(Delta760-762) mice were compared with wild-type beta3(+/+) littermates, beta3(+/-) heterozygotes, and knockin mice where beta3 RGT was replaced by beta1 C-terminal cysteine-glycine-lysine (EGK) to potentially enable signaling by Src kinases other than c-Src. Whereas beta3(+/+), beta3(+/-) and beta3/beta1(EGK) platelets spread and underwent tyrosine phosphorylation normally on fibrinogen, beta3(Delta760-762) platelets spread poorly and exhibited reduced tyrosine phosphorylation of c-Src substrates, including beta3 (Tyr(747)). Unlike control mice, beta3(Delta760-762) mice were protected from carotid artery thrombosis after vessel injury with FeCl(3). Some beta3(Delta760-762) mice exhibited prolonged tail bleeding times; however, none demonstrated spontaneous bleeding, excess bleeding after surgery, fecal blood loss, or anemia. Fibrinogen binding to beta3(Delta760-762) platelets was normal in response to saturating concentrations of protease-activated receptor 4 or glycoprotein VI agonists, but responses to adenosine diphosphate were impaired. Thus, deletion of beta3 RGT disrupts c-Src-mediated alphaIIbbeta3 signaling and confers protection from arterial thrombosis. Consequently, targeting alphaIIbbeta3 signaling may represent a feasible antithrombotic strategy.

• Authors: Ararat J Ablooglu, Jian Kang, Brian G Petrich, Mark H Ginsberg, Sanford J Shattil
• Journal: Blood (Blood) Vol. 113 Issue 15 Pg. 3585-92 (Apr 09 2009) ISSN: 1528-0020 [Electronic] United States
• PMID: 19005179 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Platelet Glycoprotein GPIIb-IIIa Complex
• Fibrinogen
• src-Family Kinases

Topics

• Animals
• Blood Platelets (physiology)
• Fibrinogen (metabolism)
• Gene Knock-In Techniques
• Hemorrhage (prevention & control)
• Hemostasis (physiology)
• Mice
• Mice, Mutant Strains
• Platelet Glycoprotein GPIIb-IIIa Complex (chemistry, genetics, metabolism)
• Protein Structure, Tertiary
• Signal Transduction (physiology)
• Thrombosis (metabolism, physiopathology, prevention & control)
• src-Family Kinases (metabolism)