PEDF regulates vascular permeability by a γ-secretase-mediated pathway

Area of Science:

• Vascular biology
• Molecular medicine
• Ophthalmology

Background:

• Increased vascular permeability is a key factor in vascular complications like diabetic retinopathy.
• Pigment epithelium-derived factor (PEDF) previously showed inhibition of vascular endothelial growth factor (VEGF)-induced angiogenesis via a γ-secretase pathway.

Purpose of the Study:

• To investigate if PEDF's inhibition of VEGF-induced vascular permeability is also γ-secretase-mediated.
• To elucidate the underlying mechanisms of PEDF's effect on vascular permeability.

Main Methods:

• In vitro assessment of vascular permeability using transendothelial electrical resistance and dextran permeability assays.
• In vivo evaluation of retinal vascular leakage in mice.
• Immunohistochemistry for adherens junction (AJ) and tight junction (TJ) proteins.
• Immunoprecipitation and Western Blot analysis to determine protein interactions and expression.

Main Results:

• PEDF's inhibition of VEGF-induced permeability in endothelial cells and mouse retinas is mediated by γ-secretase.
• PEDF prevents the dissociation of AJ and TJ proteins and regulates VEGF receptor association with AJ proteins.
• γ-secretase association with AJ proteins is critical for regulating vascular permeability; hypoxia disrupts VEGFR-AJ protein association.

Conclusions:

• PEDF regulates VEGF-induced vascular permeability through a novel γ-secretase-dependent pathway.
• Targeting downstream effectors of PEDF action presents a promising therapeutic strategy for managing increased vascular permeability.