ARNO regulates VEGF-dependent tissue responses by stabilizing endothelial VEGFR-2 surface expression

Area of Science:

• Endothelial cell biology
• Molecular signaling
• Angiogenesis research

Background:

• Vascular endothelial growth factor (VEGF) drives angiogenesis, vital for ischemic diseases.
• ADP-ribosylation factor nucleotide-binding site opener (ARNO) is a guanine exchange factor involved in cellular signaling.
• The specific role of ARNO in VEGF-mediated endothelial functions remained undocumented.

Purpose of the Study:

• To investigate the role of ARNO in VEGF-dependent endothelial cell activation.
• To determine ARNO's involvement in VEGF-induced vessel permeability.

Main Methods:

• ARNO expression confirmed via RT-PCR, Western blotting, and immunofluorescence in vitro and immunohistochemistry ex vivo.
• VEGF-dependent Akt activation and endothelial cell proliferation assessed using cytohesin inhibitor SecinH3 and ARNO siRNA.
• VEGF-induced permeability measured in vivo via FITC-dextran extravasation.
• VEGFR-2 surface expression, internalization, and degradation analyzed by flow cytometry and Western blotting.

Main Results:

• ARNO is expressed in endothelial cells.
• ARNO inhibition or knockdown blocked VEGF-induced Akt activation and endothelial cell proliferation.
• ARNO suppression reduced VEGF-induced vascular permeability in vivo.
• ARNO knockdown accelerated VEGFR-2 internalization and degradation following VEGF stimulation.

Conclusions:

• Endothelial ARNO plays a novel role in initiating VEGF-dependent angiogenesis.
• ARNO regulates VEGFR-2 internalization, impacting Akt pathway activation, vessel permeability, and endothelial proliferation.
• ARNO emerges as a potentially essential mediator in endothelial signaling and angiogenesis.