Using Self-Assembled Monolayers To Understand α8β1-Mediated Cell Adhesion to RGD and FEI Motifs in Nephronectin

Nephronectin is an extracellular matrix protein that interacts with the α8β1 integrin receptor and plays a role in tissue and organ development, though the motifs that mediate adhesion to the receptor remain unclear. This paper describes the use of self-assembled monolayers to study the adhesion of α8β1-presenting cells to the RGD and DLFEIFEIER ligands in nephronectin and found that both ligands can independently mediate cell adhesion through nonoverlapping binding sites on the integrin. Peptide truncation experiments showed FEI to be the minimal binding sequence within the DLFEIFEIER sequence, and adhesion experiments with peptides that include both the RGD and FEI sequences demonstrate that the two peptides bind synergistically to the receptor. Finally, a peptide array was used to establish a strict requirement for the glutamate residue of FEI and tolerance of other aromatic and hydrophobic residues in the first and third positions, respectively. This work provides an enhanced understanding of the binding of nephronectin with α8β1 and identifies a peptide ligand that can be used for targeting the α8β1 integrin.