Identification and characterization of Nanobodies targeting the EphA4 receptor

The ephrin receptor A4 (EphA4) plays a role in cell interactions and neurological disorders. Blocking EphA4 could be a therapeutic strategy. The study generated Nanobodies against the ligand-binding domain of the human EphA4 receptor. Two Nanobodies, Nb 39 and Nb 53, were identified that bind EphA4 with high affinity. These Nanobodies displaced all known EphA4-binding ephrins from the receptor and inhibited ephrin-induced phosphorylation. In neuron cultures, both Nanobodies inhibited EphA4-mediated growth-cone collapse induced by ephrin-B3. The results demonstrate the potential of Nanobodies to target the ligand-binding domain of EphA4 for therapeutic use.

• 1
  Two Nanobodies (Nb 39 and Nb 53) bind EphA4 with nanomolar affinities and are selective for EphA4, with some binding to EphA7.
• 2
  Nb 39 and Nb 53 displaced all known EphA4-binding ephrins from the receptor and inhibited ephrin-induced phosphorylation of the EphA4 protein in a cell-based assay.
• 3
  Both Nanobodies inhibited endogenous EphA4-mediated growth-cone collapse induced by ephrin-B3 in cortical neuron primary cultures.