Effect of RGD secondary structure and the synergy site PHSRN on cell adhesion, spreading and specific integrin engagement

The relationship between the form of cell adhesion, ligand presentation. and cell receptor function was characterized using model Langmuir-Blodgett supported films, containing lipid-conjugated peptide ligands, in which isolated variables of the ligand presentation were systematically altered. First, the conformation of all adhesive Arginine-Glycine-Aspartic acid (RGD) peptide was varied by synthesizing linear and looped RGD peptide-containing amphiphiles and subsequently measuring the impact on the function of human umbilical vein endothelial cells. Secondly, the contribution of non-contiguous ligands to cellular engagement was assessed using Multicomponent biomimetic films. The peptide amphiphiles were composed of fibronectin-derived headgroups-GRGDSP, and its synergy site Pro-His-Ser-Arg-Asn (PHSRN)-attached to hydrocarbon tails. The peptide amphiphiles were diluted using polyethylene glycol (PEG) amphiphiles, where PEG inhibited non-specific cell adhesion. Cells adhered and spread on GRGDSP/PEG systems in a dose-dependent manner. The presentation of GRGDSP influenced integrin cell surface receptor specificity. Results demonstrated that beta(1)-containing integrins mediated adhesion to the linear GRGDSP presentation to a greater extent than did the alpha(v)beta(3) integrin, and looped GRGDSP preferentially engaged alpha(v)beta(3). GRGDSP/PHSRN/PEG mixtures that closely mimicked the RGD-PHSRN distance ill fibronectin, enhanced cell spreading over their two-component analogues. This study demonstrated that controlling the microenvironment of the cell was essential for biomimetics to modulate specific binding and subsequent signaling events. (c) 2006 Elsevier Ltd. All rights reserved.