Immobilized Arg-Gly-Asp (RGD) peptides of varying lengths as structural probes of the platelet glycoprotein IIb/IIIa receptor

Abstract

The interactions between ligands containing the recognition sequence arginine-glycine-aspartic acid (RGD) and integrin receptors are important in many cell-cell and cell-protein interactions. The platelet contains five integrin receptors and they contribute significantly to platelet adhesion and aggregation. To investigate the RGD binding domains on platelet integrins, we immobilized a series of RGD peptides containing variable numbers of glycine residues [(G)n-RGDF] on polyacrylonitrile beads and evaluated the ability of the beads to interact with platelets. With native platelets, virtually no interaction occurred with G1-RGDF beads, but the interactions increased as the number of glycine residues increased, plateauing with the G9- RGDF and G11-RGDF beads. ADP pretreatment enhanced the interactions with all of the beads, whereas prostaglandin E1 pretreatment eliminated the interactions with the shortest peptide beads, but only partially inhibited interactions with the longer peptide beads. Monoclonal antibodies to glycoprotein (GP) IIb/IIIa were most effective in inhibiting the interactions, but antibodies to GPIIb/IIIa with similar inhibitory effects on fibrinogen binding varied dramatically in their ability to inhibit the interaction between platelets and immobilized RGD peptides. Our data indicate that the majority of RGD binding sites on GPIIb/IIIa can be reached by peptides that extend out approximately 11 to 32 A from the surface of the bead, and these results are in accord with the dimensions of integrin receptors deduced from electron microscopy. Activation of GPIIb/IIIa facilitates the interactions, but platelet inhibition fails to eliminate the interactions with the longer peptide beads, suggesting that access to the RGD binding site on at least a fraction of the GPIIb/IIIa receptors is always possible for preferred ligands. Finally, we found that the G3-RGDF peptide beads were uniquely sensitive to the activation state of the GPIIb/IIIa receptor.

Hemostatic effects of fibrinogen γ‐chain dodecapeptide‐conjugated polymerized albumin particles in vitro and in vivo

“…Recently, we focused on H12, which exists only in fibrinogen domain 23‐30 . Based on our result obtained from flow cytometric analyses of agglutination, the H12‐conjugated latex beads showed minimal interaction with nonactivated PLTs in comparison with RGD‐conjugated latex beads 31 .…”

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

“…Interestingly, in the studies conducted by Takeoka et al with CGGRGDF‐decorated particle systems, it was found that these particles could promote activation (and subsequent aggregation) of inactive platelets . Similar effects of linear RGDS‐containing peptides have also been reported by Du et al and Beer et al Furthermore, the RGD tri‐peptide sequence is known to have ubiquitous cell‐ and matrix‐recognition capabilities . In fact, this sequence has been reported in a variety of research including targeting to tumor cells, endothelial cells, bone cells, etc.…”

Effect of RGD‐Immobilized Dual‐Pore Poly(l‐Lactic Acid) Scaffolds on Chondrocyte Proliferation and Extracellular Matrix Production

“…Although an optimal RGD concentration would vary in cell or substrate types, currently immobilized GRGD peptide seems to be reasonable to induce the adhesion, spreading, and proliferation of chondrocyte. In addition to the amounts of the peptide on the surface, the RGD spacing in which the peptide keeps a certain minimum spacing is considered crucial for improving the cell attachment (29). In addition, it was notable that a switch of single amino acid (RGD→RDG) could make a significant difference on the chondroycte responses, demonstrating the excellent specificity of the RGD–cell receptor interactions.…”