Vipegitide: a folded peptidomimetic partial antagonist of α2β1 integrin with antiplatelet aggregation activity

Abstract

Linear peptides containing the sequence WKTSRTSHY were used as lead compounds to synthesize a novel peptidomimetic antagonist of α2β1 integrin, with platelet aggregation-inhibiting activity, named Vipegitide. Vipegitide is a 13-amino acid, folded peptidomimetic molecule, containing two α-aminoisobutyric acid residues at positions 6 and 8 and not stable in human serum. Substitution of glycine and tryptophan residues at positions 1 and 2, respectively, with a unit of two polyethylene glycol (PEG) molecules yielded peptidomimetic Vipegitide-PEG2, stable in human serum for over 3 hours. Vipegitide and Vipegitide-PEG2 showed high potency (7×10−10 M and 1.5×10−10 M, respectively) and intermediate efficacy (40% and 35%, respectively) as well as selectivity toward α2 integrin in inhibition of adhesion of α1/α2 integrin overexpressing cells toward respective collagens. Interaction of both peptidomimetics with extracellular active domain of α2 integrin was confirmed in cell-free binding assay with recombinant α2 A-domain. Integrin α2β1 receptor is found on the platelet membrane and triggers collagen-induced platelet aggregation. Vipegitide and Vipegitide-PEG2 inhibited α2β1 integrin-mediated adhesion of human and murine platelets under the flow condition, by 50%. They efficiently blocked adenosine diphosphate- and collagen I-induced platelet aggregation in platelet rich plasma and whole human blood. Higher potency of Vipegitide than Vipegitide-PEG2 is consistent with results of computer modeling of the molecules in water. These peptidomimetic molecules were acutely tolerated in mice upon intravenous bolus injection of 50 mg/kg. These results underline the potency of Vipegitide and Vipegitide-PEG2 molecules as platelet aggregation-inhibiting drug lead compounds in antithrombotic therapy.

Platelets promote breast cancer cell MCF-7 metastasis by direct interaction: surface integrin α2β1-contacting-mediated activation of Wnt-β-catenin pathway

“…As reported, integrin α2β1 is a collagen receptor which can bind to type I, II, III, IV, and XI collagens [33]. Although little is known concerning the integrin α2β1-mediated cell contacting, a previous study revealed that the inhibition of the binding between integrin α2β1 and collagen suppressed platelet aggregation [34], suggesting collagen may mediate the binding between integrins. Plus, collagens are the essential component of ECM and provide both integrity and biological cues for cells [35].…”

Anti-thrombotic agents derived from snake venom proteins

“…In contrast to the first anti- aggregation agent, the chimeric monoclonal c7E3Fab (Abciximab, Reopro) a mAb raised against αIIbβ3 [ 19 ], tirofiban and eptifibatide are small-mass αIIbβ3 antagonists derived from snake venom disintegrins. Vipegitide, a folded KTS-containing peptidomimetic molecule, inhibited the adhesion of α1/α2 integrin toward collagen, and ADP and collagen-I induced platelet aggregation in PRP and whole human blood [ 20 ], providing strategy for developing α2β1 antagonists as antiplatelet agents.…”

Dramatic and concerted conformational changes enable rhodocetin to block α2β1 integrin selectively

“…Defect or dysfunction of integrins, in particular of α2β1 integrin, a prominent collagen binding receptor of many cell types [ 3 ] and the only collagen binding integrin on platelets [ 4 ], may affect vascular development and angiogenesis [ 5 ], epithelial cell differentiation [ 6 ], wound repair and fibrosis [ 7 ], inflammation [ 8 , 9 ], and cancer and cancer therapy [ 10 ], as well as collagen-induced platelet activation, hemostasis, and thrombosis [ 4 , 11 ]. Therefore, α2β1 integrin has become a prominent target in drug research [ 12 – 14 ].…”