Inhibition of αIIbβ3 Ligand Binding by an αIIb Peptide that Clasps the Hybrid Domain to the βI Domain of β3.
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.
SGC, University of Oxford, Oxford, United Kingdom.
Wen Hwa
WH
Lee
Laboratoire de Biologie et Physiologie Intégrée, (CNRS/GDRE-ITI), University of Luxembourg, Luxembourg City, Luxembourg.
Elisabeth
E
Schaffner-Reckinger
Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece.
Demokritos C
DC
Tsoukatos
Inserm UMR_S 1140, Faculté de pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
Kelly
K
Aylward
Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece.
Vassilios
V
Moussis
Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece.
Vassilios
V
Tsikaris
Department of Chemistry, Section of Organic Chemistry and Biochemistry, Ioannina, Greece.
Paraskevi
P
Trypou
Inserm UMR_S 1140, Faculté de pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
Marion
M
Egot
Inserm UMR_S 1140, Faculté de pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
Dominique
D
Baruch
Laboratoire de Biologie et Physiologie Intégrée, (CNRS/GDRE-ITI), University of Luxembourg, Luxembourg City, Luxembourg; CNRS-LIA124, Sino-French Research Center for Life Sciences and Genomics, Rui Jin Hospital, Jiao Tong University School of Medicine, Shanghai, China.
Nelly
N
Kieffer
Inserm UMR_S 1140, Faculté de pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
Christilla
C
Bachelot-Loza
D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D039421:Integrin alpha2 / Q000378:metabolism*; D015539:Platelet Activation; D010974:Platelet Aggregation / Q000502:physiology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism*; D011485:Protein Binding
D039421:Integrin alpha2; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D040201:Platelet Membrane Glycoprotein IIb; D005340:Fibrinogen