von Hippel-Lindau tumor suppressor mutants faithfully model pathological hypoxia-driven angiogenesis and vascular retinopathies in zebrafish.

Abstract

Biallelic inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene predisposes human patients to the development of highly vascularized neoplasms in multiple organ systems. We show that zebrafish vhl mutants display a marked increase in blood vessel formation throughout the embryo, starting at 2 days post-fertilization. The most severe neovascularization is observed in distinct areas that overlap with high vegfa mRNA expression, including the vhl mutant brain and eye. Real-time quantitative PCR revealed increased expression of the duplicated VEGFA orthologs vegfaa and vegfab, and of vegfb and its receptors flt1, kdr and kdr-like, indicating increased vascular endothelial growth factor (Vegf) signaling in vhl mutants. Similar to VHL-associated retinal neoplasms, diabetic retinopathy and age-related macular degeneration, we show, by tetramethyl rhodamine-dextran angiography, that vascular abnormalities in the vhl(-/-) retina lead to vascular leakage, severe macular edema and retinal detachment. Significantly, vessels in the brain and eye express cxcr4a, a marker gene expressed by tumor and vascular cells in VHL-associated hemangioblastomas and renal cell carcinomas. VEGF receptor (VEGFR) tyrosine kinase inhibition (through exposure to sunitinib and 676475) blocked vhl(-/-)-induced angiogenesis in all affected tissues, demonstrating that Vegfaa, Vegfab and Vegfb are key effectors of the vhl(-/-) angiogenic phenotype through Flt1, Kdr and Kdr-like signaling. Since we show that the vhl(-/-) angiogenic phenotype shares distinct characteristics with VHL-associated vascular neoplasms, zebrafish vhl mutants provide a valuable in vivo vertebrate model to elucidate underlying mechanisms contributing to the development of these lesions. Furthermore, vhl mutant zebrafish embryos carrying blood vessel-specific transgenes represent a unique and clinically relevant model for tissue-specific, hypoxia-induced pathological angiogenesis and vascular retinopathies. Importantly, they will allow for a cost-effective, non-invasive and efficient way to screen for novel pharmacological agents and combinatorial treatments.

• Authors: Ellen van Rooijen, Emile E Voest, Ive Logister, Jeroen Bussmann, Jeroen Korving, Fredericus J van Eeden, Rachel H Giles, Stefan Schulte-Merker
• Journal: Disease models & mechanisms (Dis Model Mech) 2010 May-Jun Vol. 3 Issue 5-6 Pg. 343-53 ISSN: 1754-8411 [Electronic] England
• PMID: 20335444 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Mutant Proteins
• Tumor Suppressor Proteins
• Vhl protein, zebrafish
• Zebrafish Proteins
• Receptors, Vascular Endothelial Growth Factor

Topics

• Animals
• Disease Models, Animal
• Edema (complications, pathology)
• Humans
• Hypoxia (complications, pathology)
• Macula Lutea (metabolism, pathology)
• Mutant Proteins (metabolism)
• Mutation (genetics)
• Receptors, Vascular Endothelial Growth Factor (antagonists & inhibitors, metabolism)
• Retinal Detachment (complications, pathology)
• Retinal Neovascularization (complications, enzymology, pathology)
• Signal Transduction
• Tumor Suppressor Proteins (genetics, metabolism)
• Zebrafish (metabolism)
• Zebrafish Proteins (genetics, metabolism)