Structure–Activity Relationships of RGD-Containing Peptides in Integrin αvβ5-Mediated Cell Adhesion

[Image: see text] The RGD motif is a cell adhesion sequence that binds to integrins, a receptor family for extracellular matrix proteins. We previously reported that the RGDX(1)X(2) sequence, where X(1)X(2) is VF or NY, is required for integrin αvβ5-mediated cell adhesion. However, the importance and applications of the X(1)X(2) combinations and their surrounding sequences of integrin αvβ5-binding RGDX(1)X(2)-containing peptides have not been comprehensively elucidated. Therefore, we aimed to identify an RGD-containing peptide with enhanced integrin αvβ5 binding activity. We synthesized various peptides based on the RGDVF and RGDNY peptides to optimize the N-terminal, C-terminal, and X(1)X(2) combinations of the RGDX(1)X(2) sequence. These peptides were immobilized on maleimide-functionalized bovine serum albumin-coated plates via a thiol-maleimide reaction, and cell adhesion was evaluated using HeLa cells and human dermal fibroblasts. Consequently, CPPP-RGDTF and CPPP-RGDTFI were identified as highly active peptides for integrin αvβ5-mediated cell adhesion. CPPP-RGDTF and CPPP-RGDTFI are expected to serve as cell adhesion molecules for developing culture substrates and biomaterials. Furthermore, these findings provide important novel insights into the interaction between the RGD motifs and integrins.