Structure–activity relationships of α<sub>IIb</sub> 313–320 derived peptide inhibitors of human platelet aggregation

Stanica, Ruxandra Maria; Benaki, Dimitra; Rodis, Foteini I.; Mikros, Emmanuel; Tsoukatos, Dimokritos; Tselepis, Alexandros D.; Tsikaris, V

doi:10.1002/psc.1060

Cited by 3 publications

(2 citation statements)

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“…The octapeptide p YMESRADR derived from integrin αIIb, previously shown to inhibit platelet aggregation by blocking fibrinogen binding to activated αIIbβ3 [ 27 ], corresponds to residues 313–320 of the insert loop (β-ribbon), that extends between the β2 and β3 strands of the W5 blade of the αIIb β-propeller domain [ 5 ]. The crystal structure of the bent-closed β3 subunit conformation tightly accommodates this loop in a cleft formed between the βI, hybrid and the third and fourth I-EGF domains of β3.…”

Section: Resultsmentioning

confidence: 99%

“…We then revisited our data from a previous NMR structural and functional characterisation of the native octapeptide and its alanine scanning substitutions [ 27 ]. Upon examination of the solution conformational ensembles, it was clear that the backbone conformation of the native peptide in solution was being stabilized via an intra-molecular salt-bridge formed by p R317 and p D319 ( Fig 5A ).…”

Section: Resultsmentioning

confidence: 99%

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Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

et al. 2015

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Agonist-stimulated platelet activation triggers conformational changes of integrin αIIbβ3, allowing fibrinogen binding and platelet aggregation. We have previously shown that an octapeptide, p1YMESRADR8, corresponding to amino acids 313–320 of the β-ribbon extending from the β-propeller domain of αIIb, acts as a potent inhibitor of platelet aggregation. Here we have performed in silico modelling analysis of the interaction of this peptide with αIIbβ3 in its bent and closed (not swing-out) conformation and show that the peptide is able to act as a substitute for the β-ribbon by forming a clasp restraining the β3 hybrid and βI domains in a closed conformation. The involvement of species-specific residues of the β3 hybrid domain (E356 and K384) and the β1 domain (E297) as well as an intrapeptide bond (pE315-pR317) were confirmed as important for this interaction by mutagenesis studies of αIIbβ3 expressed in CHO cells and native or substituted peptide inhibitory studies on platelet functions. Furthermore, NMR data corroborate the above results. Our findings provide insight into the important functional role of the αIIb β-ribbon in preventing integrin αIIbβ3 head piece opening, and highlight a potential new therapeutic approach to prevent integrin ligand binding.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

et al. 2015

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Conformational Studies of the 313-320 and 313-332 Peptide Fragments Derived from the αIIb Subunit of Integrin Receptor with Molecular Dynamics Simulations

Stavrakoudis

2009

Int J Pept Res Ther

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Inhibition of platelet activation by peptide analogs of theβ₃-intracellular domain of platelet integrinα_IIbβ₃conjugated to the cell-penetrating peptide Tat(48–60)

Dimitriou¹,

Stathopoulos²,

Mitsios³

et al. 2009

Platelets

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Activation of the platelet integrin-receptor alpha(IIb)beta(3) is the final pathway of platelet aggregation, regardless of the initiating stimulus. Many studies suggest that there are several cytoplasmic proteins such as talin and beta(3)-endonexin that bind to N(744)PLY(747) and N(756)ITY(759) motif of the beta(3) cytoplasmic tail and play the major role in the receptor activation. In this study, we investigated the role of the membrane distal region of human beta(3) cytoplasmic tail and specifically the N(743)NPLYKEA(750) and T(755)NITYRGT(762) sequence that contains an NXXY motif, in platelet aggregation, secretion, alpha(IIb)beta(3) activation (PAC-1 binding) and fibrinogen binding. We synthesized two peptides corresponding to the above sequences as well as their conjugates with the Tat(48-60) cell-penetrating peptide. The capability of conjugates to penetrate the platelet membrane was investigated with confocal laser scanning microscopy using carboxyfluorescein (CF)-labeled peptides. Our results showed that the conjugated with the Tat(48-60) sequence peptides penetrate the platelet membrane and inhibit platelet aggregation in both PRP and washed platelets in a dose-dependent manner. The Tat-beta(3)743-750 conjugate exhibited similar inhibitory activity in PRP and in washed platelets whereas the Tat-beta(3)755-762 conjugate was more potent inhibitor of aggregation in washed platelets than in PRP. Both conjugated peptides were also able to inhibit P-selectin membrane expression as well as PAC-1 and fibrinogen binding to the platelets, the Tat-beta(3)755-762 conjugate being more potent than Tat-beta(3)743-750. The Tat(48-60) peptide and the peptides beta(3)743-750 and beta(3)755-762, which were not conjugated to the Tat(48-60) sequence, did not exhibit any inhibitory effect on the above parameters. In conclusion, the present study shows for the first time that the peptide analogs of the intracellular domain of the beta(3) subunit beta(3)743-750 and beta(3)755-762 conjugated to the cell-penetrating peptide Tat(48-60) are capable of penetrating the platelet membrane and expressing biological activity by inhibiting the activation of alpha(IIb)beta(3), the fibrinogen binding to the activated receptor as well as platelet aggregation. Further studies are necessary to support whether such conjugated peptides may be useful tools for the development of potent antiplatelet agents acting intracellularly through the platelet integrin alpha(IIb)beta(3).

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Structure–activity relationships of α_IIb 313–320 derived peptide inhibitors of human platelet aggregation

Cited by 3 publications

References 32 publications

Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

Conformational Studies of the 313-320 and 313-332 Peptide Fragments Derived from the αIIb Subunit of Integrin Receptor with Molecular Dynamics Simulations

Inhibition of platelet activation by peptide analogs of theβ₃-intracellular domain of platelet integrinα_IIbβ₃conjugated to the cell-penetrating peptide Tat(48–60)

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Structure–activity relationships of αIIb 313–320 derived peptide inhibitors of human platelet aggregation

Cited by 3 publications

References 32 publications

Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3

Conformational Studies of the 313-320 and 313-332 Peptide Fragments Derived from the αIIb Subunit of Integrin Receptor with Molecular Dynamics Simulations

Inhibition of platelet activation by peptide analogs of theβ3-intracellular domain of platelet integrinαIIbβ3conjugated to the cell-penetrating peptide Tat(48–60)

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Structure–activity relationships of α_IIb 313–320 derived peptide inhibitors of human platelet aggregation

Inhibition of platelet activation by peptide analogs of theβ₃-intracellular domain of platelet integrinα_IIbβ₃conjugated to the cell-penetrating peptide Tat(48–60)