title: Frizzled 4 is required for retinal angiogenesis and maintenance of the blood-retina barrier.
abstract: PURPOSE. Mice deficient in the secreted protein Norrin or its receptor Frizzled-4 (FZD4) exhibit incomplete vascularization of the neural retina. However, because of early retinal vascular defects in the knockout models, it has not been possible to study FZD4 contribution in ocular neovascular disease. To further understand the role of this signaling pathway in physiological and pathologic angiogenesis, the authors generated a monoclonal antibody that neutralizes FZD4 function in vivo. METHODS. Antibodies were generated by immunizing Fzd4 knockout mice with the cysteine-rich domain of FZD4. A monoclonal antibody (1.99.25) was discovered that antagonizes Norrin- and WNT3A-induced β-catenin accumulation in vitro. 1.99.25 and an isotype-matched negative control antibody were evaluated in models of developmental retinal angiogenesis, oxygen-induced retinopathy, and retinal angiomatous proliferation. The authors also investigated the role of FZD4 in maintaining the blood-retina barrier in normal adult mice. RESULTS. Administration of 1.99.25 inhibited physiological and pathologic sprouting angiogenesis within the retina. Inhibition of FZD4 in developing retinal vascular networks caused the upregulation of PLVAP, a protein normally associated with fenestrated, immature endothelium in the CNS. In the adult neural retina, the administration of 1.99.25 induced PLVAP expression in the deep capillary bed and enabled extravasation of small and large molecules through the blood-retina barrier. CONCLUSIONS. These results demonstrate that FZD4 is required for physiological and pathologic angiogenesis in the retina and for regulation of retinal endothelial cell differentiation. The authors also show that FZD4 is critical for maintaining the integrity of the mature blood-retina barrier.
authors: Departments of Ophthalmology, Lexicon Pharmaceuticals, Inc., The Woodlands, Texas, USA.
authors: Kim T
authors: KT
authors: Paes
authors: Ernest
authors: E
authors: Wang
authors: Kathy
authors: K
authors: Henze
authors: Peter
authors: P
authors: Vogel
authors: Robert
authors: R
authors: Read
authors: Adisak
authors: A
authors: Suwanichkul
authors: Laura L
authors: LL
authors: Kirkpatrick
authors: David
authors: D
authors: Potter
authors: Matthew M
authors: MM
authors: Newhouse
authors: Dennis S
authors: DS
authors: Rice
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D001813:Blood-Retinal Barrier / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000037:antagonists & inhibitors; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D051157:Frizzled Receptors / Q000037:antagonists & inhibitors / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000633:toxicity; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000502:physiology*; D011973:Receptors, LDL / Q000378:metabolism; D015861:Retinal Neovascularization / Q000139:chemically induced / Q000378:metabolism* / Q000517:prevention & control; D012171:Retinal Vessels / Q000187:drug effects / Q000502:physiology
chemical_list: D057134:Antibodies, Neutralizing; D005136:Eye Proteins; D051157:Frizzled Receptors; C498581:Fzd4 protein, mouse; C489916:Ndph protein, mouse; D009419:Nerve Tissue Proteins; D043562:Receptors, G-Protein-Coupled; D011973:Receptors, LDL; C036053:VLDL receptor; D010100:Oxygen