VEGF-A splice variants bind VEGFRs with differential affinities

Area of Science:

• Molecular biology
• Biochemistry
• Cell signaling

Background:

• Vascular endothelial growth factor A (VEGF-A) is a key regulator of angiogenesis.
• VEGF-A exists in multiple splice variants, including VEGF-A_165a, VEGF-A₁₂₁, and VEGF-A_165b.
• The differential binding kinetics of these splice variants to VEGF receptors (VEGFRs) are not fully understood.

Purpose of the Study:

• To experimentally determine the binding kinetics of VEGF-A₁₆₅, VEGF-A_165b, and VEGF-A₁₂₁ with VEGFR1 and VEGFR2.
• To compare the binding affinities of different VEGF-A splice variants to their receptors.
• To elucidate the differential receptor binding of pro- and anti-angiogenic VEGF-A isoforms.

Main Methods:

• Surface plasmon resonance (SPR) was used to measure binding kinetics.
• Known affinities of VEGF-A_165a:VEGFR1, VEGF-A_165a:VEGFR2, and VEGF-A₁₂₁:VEGFR2 were reproduced for method validation.
• Binding affinities of VEGF-A₁₆₅, VEGF-A_165b, and VEGF-A₁₂₁ to VEGFR1 and VEGFR2 were quantified.

Main Results:

• Methods were validated by reproducing known binding affinities.
• VEGF-A₁₂₁ binds VEGFR1 with an affinity of K_D = 3.7 nM.
• VEGF-A_165b selectively binds VEGFR2 with high affinity (K_D = 0.67 pM) and VEGFR1 with lower affinity (K_D = 1.4 nM).

Conclusions:

• The anti-angiogenic VEGF-A_165b variant demonstrates a strong preference for VEGFR2 binding.
• These findings suggest a distinct role for VEGF-A_165b in angiogenesis regulation via preferential VEGFR2 interaction.
• Differentiating VEGF-A splice variants is crucial for future research in vascular biology and disease.