RGDX 1 X 2 motif regulates integrin αvβ5 binding for pluripotent stem cell adhesion.

The arginine-glycine-aspartic acid (RGD) motif is a cell adhesion sequence that binds to integrins. Some RGD-containing peptides promote adhesion of both embryonic stem cells and induced pluripotent stem cells (iPSCs); however, not all such RGD-containing peptides are active. In this study, we elucidated the role of RGD-neighboring sequences on iPSC adhesion using diverse synthetic peptides and recombinant proteins. Our results indicate that iPSC adhesion requires RGDX 1 X 2  sequences, such as RGDVF and RGDNY, and that the X 1 X 2 residues are essential for the adhesion via integrin αvβ5 but not αvβ3. iPSCs express integrin αvβ5 but not αvβ3; therefore, iPSC adhesion requires the RGDX 1 X 2 -containing sequences. The importance of the X 1 X 2 residues was confirmed with both HeLa and A549 cells, which express integrin αvβ5 but not αvβ3. Analysis of RGD-neighboring sequences provides important insights into ligand-binding specificity of integrins. Identification of integrin αvβ5-binding motifs is potentially useful in drug development, drug delivery, cell culture, and tissue engineering.