In vitro and in vivo models analyzing von Hippel-Lindau disease-specific mutations.
Mutations in the von Hippel-Lindau (VHL) tumor suppressor gene cause tissue-specific tumors, with a striking genotype-phenotype correlation. Loss of VHL expression predisposes to hemangioblastoma and clear cell renal cell carcinoma, whereas specific point mutations predispose to pheochromocytoma, polycythemia, or combinations of hemangioblastoma, renal cell carcinoma, and/or pheochromocytoma. The VHL protein (pVHL) has been implicated in many cellular activities including the hypoxia response, cell cycle arrest, apoptosis, and extracellular matrix remodeling. We have expressed missense pVHL mutations in Vhl(-/-) murine embryonic stem cells to test genotype-phenotype correlations in euploid cells. We first examined the ability of mutant pVHL to direct degradation of the hypoxia inducible factor (HIF) subunits HIF1alpha and HIF2alpha. All mutant pVHL proteins restored proper hypoxic regulation of HIF1alpha, although one VHL mutation (VHL(R167Q)) displayed impaired binding to Elongin C. This mutation also failed to restore HIF2alpha regulation. In separate assays, these embryonic stem cells were used to generate teratomas in immunocompromised mice, allowing independent assessment of the effects of specific VHL mutations on tumor growth. Surprisingly, teratomas expressing the VHL(Y112H) mutant protein displayed a growth disadvantage, despite restoring HIFalpha regulation. Finally, we observed increased microvessel density in teratomas derived from Vhl(-/-) as well as VHL(Y112H), VHL(R167Q), and VHL(R200W) embryonic stem cells. Together, these observations support the hypothesis that pVHL plays multiple roles in the cell, and that these activities can be separated via discrete VHL point mutations. The ability to dissect specific VHL functions with missense mutations in a euploid model offers a novel opportunity to elucidate the activities of VHL as a tumor suppressor.
Rathmell
W Kimryn
WK
Abramson Family Cancer Research Institute and the Department of Cell and Molecular Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Hickey
Michele M
MM
Bezman
Natalie A
NA
Chmielecki
Christie A
CA
Carraway
Natalie C
NC
Simon
M Celeste
MC
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D048708:Cell Growth Processes / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology; D005353:Fibronectins / Q000378:metabolism; D016147:Genes, Tumor Suppressor; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology; D013724:Teratoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D005353:Fibronectins; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D042461:Vascular Endothelial Growth Factor A; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse; C497446:VHL protein, human