Abstract
Angiogenesis and blood-brain barrier formation are required for normal central nervous system (CNS) function. Both processes are controlled by Wnt or Norrin (NDP) ligands, Frizzled (FZD) receptors, and β-catenin-dependent signalling in vascular endothelial cells. In the retina, FZD4 and the ligand NDP are critical mediators of signalling and are mutated in familial exudative vitreoretinopathy. Here, we report that NDP is a potent trigger of FZD4 ubiquitination and induces internalization of the NDP receptor complex into the endo-lysosomal compartment. Inhibition of ubiquitinated cargo transport through the multivesicular body (MVB) pathway using a dominant negative ESCRT (endosomal sorting complexes required for transport) component VPS4 EQ strongly impairs NDP/FZD4 signalling in vitro and recapitulates CNS angiogenesis and blood-CNS-barrier defects caused by impaired vascular β-catenin signalling in mice. These findings provide evidence for an important role of FZD4 endocytosis in NDP/FZD4 signalling and in CNS vascular biology and disease.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
ATPases Associated with Diverse Cellular Activities / metabolism*
-
Animals
-
Blood-Brain Barrier / metabolism*
-
Endocytosis*
-
Endosomal Sorting Complexes Required for Transport / metabolism*
-
Endosomes / metabolism
-
Endothelial Cells / metabolism*
-
Eye Diseases, Hereditary / genetics
-
Eye Diseases, Hereditary / metabolism
-
Eye Proteins / genetics
-
Eye Proteins / metabolism*
-
Familial Exudative Vitreoretinopathies
-
Frizzled Receptors / genetics
-
Frizzled Receptors / metabolism*
-
HEK293 Cells
-
HeLa Cells
-
Humans
-
In Vitro Techniques
-
Lysosomes / metabolism*
-
Mice
-
Multivesicular Bodies / metabolism
-
Mutation
-
Neovascularization, Physiologic*
-
Nerve Tissue Proteins / genetics
-
Nerve Tissue Proteins / metabolism*
-
Protein Transport
-
Retina
-
Retinal Diseases / genetics
-
Retinal Diseases / metabolism
-
Retinal Vessels / growth & development*
-
Ubiquitination
-
Vacuolar Proton-Translocating ATPases / metabolism*
-
Wnt Signaling Pathway
Substances
-
Endosomal Sorting Complexes Required for Transport
-
Eye Proteins
-
FZD4 protein, human
-
Frizzled Receptors
-
Fzd4 protein, mouse
-
NDP protein, human
-
Ndph protein, mouse
-
Nerve Tissue Proteins
-
Vacuolar Proton-Translocating ATPases
-
ATPases Associated with Diverse Cellular Activities
-
VPS4A protein, human