Selective Targeting of a Novel Epsin-VEGFR2 Interaction Promotes VEGF-Mediated Angiogenesis

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Vascular endothelial growth factor (VEGF)-induced binding of VEGF receptor 2 (VEGFR2) to epsins triggers receptor degradation and attenuates signaling.
• The epsin ubiquitin-interacting motif (UIM) is essential for VEGFR2 interaction, but specific molecular determinants were unknown.

Purpose of the Study:

• Identify critical molecular determinants governing the specific interaction between epsin and VEGFR2.
• Determine if these determinants are essential for physiological angiogenesis in vivo.

Main Methods:

• Structural modeling to identify VEGFR2 binding surfaces for epsin UIM.
• Mutational analysis of VEGFR2 and epsin residues involved in the interaction.
• In vitro assays for endothelial cell proliferation, migration, and angiogenesis.
• In vivo studies of postnatal retinal angiogenesis, wound healing, and VEGF-induced angiogenesis.

Main Results:

• Two novel binding surfaces on VEGFR2 interacting with epsin UIM were uncovered.
• Specific glutamic acid residues in epsin UIM interact with VEGFR2 residues.
• VEGF-induced interaction promotes epsin ubiquitination and reveals a VEGFR2 ubiquitin-binding surface.
• Mutational analysis confirmed the interaction relies on UIM binding and recognition of ubiquitinated epsin.
• An epsin UIM peptide enhanced endothelial cell functions and physiological angiogenesis in vitro and in vivo.

Conclusions:

• Distinct residues in epsin UIM and VEGFR2 mediate specific interactions and UIM recognition of ubiquitin moieties.
• These interactions are crucial for pathophysiological angiogenesis.
• The identified interaction sites represent potential therapeutic targets for modulating angiogenesis.