Inhibition of the EphA2-Sam/Ship2-Sam Association through Peptide Ligands: Studying the Combined Effect of Charge and Aromatic Character

The
Sam (sterile alpha motif) domain from the lipid phosphatase
Ship2 binds the Sam domain from the EphA2 receptor to negatively regulate
receptor endocytosis and degradation. This interaction is primarily
linked to pro-oncogenic effects. We report on the design and evaluation
of EphA2-Sam/Ship2-Sam peptide inhibitors provided with positive charges
and different aromatic characters. Starting from the sequence of previously
identified Ship2-Sam targeting peptides, an in silico approach was
set up to predict higher affinity peptide ligands. A few peptides
were experimentally tested through an interdisciplinary approach.
Interaction studies were performed by nuclear magnetic resonance spectroscopy
and biolayer interferometry. 3D models of Ship2-Sam/peptide complexes
were predicted by AlphaFold2. Cell-based assays were carried out to
investigate whether such peptide sequences might have an influence
on EphA2 signaling. The approach led to the identification of novel
Ship2-Sam ligands and shed further light on original approaches to
design inhibitors of the Ship2-Sam/EphA2-Sam interaction.